Quick Recipe Version (TL;DR)
Quick Ingredients
- 4 onion bagels, split
- 1 lb cooked smoked beef brisket, chopped
- 3/4–1 cup smoky BBQ sauce, divided
- 1/4 cup beef broth or water
- 2 cups shredded green cabbage
- 1 cup shredded red cabbage (or more green)
- 1/2 cup shredded carrot
- 1/3 cup mayonnaise
- 2 tbsp apple cider vinegar
- 1 tbsp Dijon mustard
- 2 tsp honey
- 1 large yellow onion, very thinly sliced
- 1 cup buttermilk
- 3/4 cup all-purpose flour
- 1/4 cup cornstarch
- 1 tsp smoked paprika
- 1/2 tsp garlic powder + 1/2 tsp onion powder
- Neutral oil for frying (about 3 cups)
- 2 tbsp unsalted butter (for toasting bagels)
- Kosher salt and black pepper
Do This
- 1. Make slaw: Whisk mayo, vinegar, mustard, honey, salt, and pepper. Toss with cabbage and carrot; chill.
- 2. Soak onions in buttermilk 15–20 minutes. Mix flour, cornstarch, paprika, garlic powder, onion powder, salt, and pepper.
- 3. Fry onion strings in 350°F (175°C) oil for 2–3 minutes until golden and crisp. Drain on paper towels; salt lightly.
- 4. Warm chopped brisket in a covered baking dish with broth and 1/4 cup BBQ sauce at 300°F (150°C) for 15 minutes, until hot and juicy.
- 5. Toast bagels in a toaster or buttered skillet until lightly crisp and golden.
- 6. Assemble: Spread BBQ sauce on bagels, pile on brisket, top with slaw and onion strings, drizzle more sauce, close, and serve immediately.
Why You’ll Love This Recipe
- It transforms leftover smoked brisket into a luxurious, deli-worthy sandwich without complicated techniques.
- The contrast of tender, saucy meat, crunchy onion strings, and cool, tangy slaw makes every bite layered and satisfying.
- Using onion bagels adds extra savory flavor and texture that stands up to all the fillings.
- Each component can be made ahead, so assembly is fast when you are ready to eat.
Grocery List
- Produce: Green cabbage, red cabbage (or bagged coleslaw mix), carrot, 1 large yellow onion, small red onion or green onions, optional jalapeños, optional fresh parsley.
- Dairy: Buttermilk, unsalted butter.
- Pantry: Onion bagels, cooked smoked beef brisket (leftover or deli), smoky BBQ sauce, apple cider vinegar, Dijon mustard, honey, mayonnaise, all-purpose flour, cornstarch, smoked paprika, garlic powder, onion powder, kosher salt, black pepper, neutral frying oil, beef broth or water, jarred pickle slices (optional).
Full Ingredients
For the Tangy Slaw
- 2 cups finely shredded green cabbage
- 1 cup finely shredded red cabbage (or additional green cabbage)
- 1/2 cup shredded carrot (about 1 medium carrot)
- 2 tbsp finely minced red onion or 2 tbsp thinly sliced green onion
- 1/3 cup mayonnaise
- 2 tbsp apple cider vinegar
- 1 tbsp Dijon mustard
- 2 tsp honey
- 1/4 tsp celery seed (optional but recommended)
- 1/2 tsp kosher salt, plus more to taste
- 1/4 tsp freshly ground black pepper
For the Crispy Onion Strings
- 1 large yellow onion, very thinly sliced into rings or half-moons
- 1 cup buttermilk (or 1 cup milk mixed with 1 tsp lemon juice, rested 5 minutes)
- 3/4 cup all-purpose flour
- 1/4 cup cornstarch
- 1 tsp smoked paprika
- 1/2 tsp garlic powder
- 1/2 tsp onion powder
- 1/2 tsp kosher salt, plus more for finishing
- 1/4 tsp freshly ground black pepper
- Neutral oil for frying (about 3 cups), such as canola, vegetable, or peanut oil
For the Brisket and Assembly
- 1 lb cooked smoked beef brisket, chopped into bite-sized pieces (about 3 to 4 cups loosely packed)
- 1/4 cup beef broth or water
- 3/4 to 1 cup smoky BBQ sauce, divided (plus more to taste for serving)
- 4 onion bagels, split horizontally
- 2 tbsp unsalted butter, softened (for toasting bagels)
- Optional: Pickle slices, thinly sliced jalapeños, or chopped fresh parsley for garnish
Step-by-Step Instructions
Step 1: Make the tangy slaw
In a medium bowl, whisk together the mayonnaise, apple cider vinegar, Dijon mustard, honey, celery seed (if using), kosher salt, and black pepper until the dressing is smooth and creamy.
Add the shredded green cabbage, shredded red cabbage, shredded carrot, and minced red onion or sliced green onions to the bowl. Toss everything together until the vegetables are evenly coated in the dressing. Taste and adjust seasoning with a pinch more salt or vinegar if you like it brighter.
Cover and refrigerate while you prepare the other components. The slaw will soften slightly and the flavors will meld as it rests, which is exactly what you want for this sandwich.
Step 2: Soak the onions for the crispy strings
Peel the yellow onion, then slice it very thinly into rings or half-moons. Aim for slices about 1/8 inch thick so they fry up quickly and get nice and crisp. Separate the slices into individual rings with your fingers.
Place the sliced onions in a medium bowl and pour the buttermilk over them. Use a spoon or your hands to make sure all the onions are submerged. Let them soak for 15 to 20 minutes. This step softens the sharpness of the onion, helps the coating stick, and encourages a light, shatteringly crisp crust.
Step 3: Dredge and fry the onion strings
While the onions soak, mix the coating. In a shallow dish or pie plate, whisk together the all-purpose flour, cornstarch, smoked paprika, garlic powder, onion powder, kosher salt, and black pepper until well combined.
Pour about 3 inches of neutral oil into a heavy-bottomed pot or deep skillet. Heat over medium to medium-high heat until the oil reaches 350°F (175°C). Use a thermometer for best results; if you do not have one, a small pinch of the flour mixture should sizzle immediately when dropped in.
Working in small handfuls, lift some onion slices from the buttermilk, allowing excess to drip off, then toss them in the flour mixture to coat thoroughly. Shake off excess flour and carefully lower the coated onions into the hot oil. Fry for 2 to 3 minutes, stirring gently, until golden brown and crisp.
Transfer the fried onion strings to a paper towel–lined plate and immediately sprinkle with a pinch of salt. Repeat with the remaining onions, letting the oil return to 350°F (175°C) between batches. Set aside.
Step 4: Warm the brisket with BBQ sauce
Preheat your oven to 300°F (150°C). Chop the cooked smoked brisket into bite-sized pieces if it is not already chopped. Place the brisket in a small baking dish that holds it in a relatively snug layer.
Pour the beef broth or water over the brisket to add moisture, then drizzle in about 1/4 cup of the BBQ sauce. Toss or stir to coat the meat evenly. Cover the dish tightly with foil to prevent it from drying out.
Warm in the preheated oven for about 15 minutes, stirring once halfway through, until the brisket is hot and juicy. If you prefer to use the stovetop, you can also warm the brisket in a covered skillet over low heat with the broth and BBQ sauce, stirring occasionally, for 8 to 10 minutes.
Step 5: Toast the onion bagels
While the brisket warms, prepare the bagels. Split the onion bagels horizontally if they are not already split. Lightly spread the cut sides with the softened butter.
Toast in a toaster or toaster oven until lightly crisp and golden. For extra flavor and a bit of char, you can also toast the bagels cut-side down in a hot skillet or grill pan for 2 to 3 minutes until golden and slightly crisp around the edges.
Keep the toasted bagel halves warm on a tray or plate while you get ready to assemble.
Step 6: Assemble the BBQ brisket bagels
Set out the toasted bagel bottoms on a work surface. Spread each bottom half with about 1 to 2 tablespoons of BBQ sauce, depending on how saucy you like it.
Divide the warm chopped brisket evenly among the bagels, piling it high. Spoon a little more BBQ sauce over the top of the meat if desired. Next, add a generous scoop of tangy slaw to each sandwich, pressing it gently so it stays in place.
Top each mound of slaw with a small handful of crispy onion strings, letting them spill over slightly for a dramatic, piled-high look. If using, add pickle slices, jalapeño slices, and a sprinkle of chopped fresh parsley.
Cap each sandwich with the top half of the onion bagel. Press gently to help everything nestle together. Serve immediately while the bagels are warm, the brisket is hot, and the onion strings are still crisp.
Pro Tips
- Slice onions very thinly: The thinner the onion slices, the lighter and crispier the onion strings will be. A mandoline works well if you have one.
- Do not overcrowd the fryer: Fry the onion strings in small batches. Overcrowding drops the oil temperature and leads to soggy, greasy onions.
- Use leftover brisket: This recipe shines with leftover smoked brisket from a BBQ day. The gentle reheat with broth and sauce keeps it moist and flavorful.
- Adjust the slaw to your taste: For more tang, add an extra teaspoon of vinegar; for a sweeter slaw, add a bit more honey.
- Warm the BBQ sauce: Gently warming the sauce before drizzling over the brisket makes the whole sandwich feel more cohesive and comforting.
Variations
- Spicy version: Stir a teaspoon of hot sauce or chipotle in adobo into the BBQ sauce, and add sliced jalapeños to the sandwiches for extra heat.
- Cheesy brisket bagel: Add a slice of sharp cheddar or pepper jack cheese on top of the warm brisket, letting it melt slightly before adding slaw and onion strings.
- Shortcut onions: In a pinch, use store-bought crispy fried onions (the kind used for green bean casserole) instead of making onion strings from scratch.
Storage & Make-Ahead
For best texture, assemble the BBQ brisket bagels right before serving. However, most components can be made ahead:
Brisket: Cooked brisket will keep in an airtight container in the refrigerator for 3 to 4 days. Reheat gently with a splash of broth and some BBQ sauce in the oven at 300°F (150°C) or on the stovetop over low heat.
Slaw: The tangy slaw can be prepared up to 1 day ahead. Store it covered in the refrigerator. It will soften slightly as it sits but remain delicious; give it a quick toss before serving.
Onion strings: These are best the day they are fried. If you have leftovers, store them loosely covered at room temperature for up to 1 day, then re-crisp on a baking sheet in a 375°F (190°C) oven for 5 to 7 minutes.
Bagels: Onion bagels can be sliced ahead and stored in a sealed bag at room temperature for 1 to 2 days, then toasted just before assembly.
Nutrition (per serving)
Approximate values per fully loaded sandwich (1 onion bagel with brisket, slaw, onion strings, and sauce): about 900–1,000 calories; 42–48 g protein; 80–90 g carbohydrates; 40–45 g fat; 8–10 g saturated fat; 4–6 g fiber; 2,000–2,400 mg sodium. Actual values will vary based on the specific BBQ sauce, brisket fat content, and portion sizes used.
