Quick Recipe Version (TL;DR)
Quick Ingredients
- 1 lb (450 g) russet potatoes, peeled and cut into 1-inch chunks
- 1 lb (450 g) cod (or other firm white fish)
- 2 tbsp unsalted butter, 2 tbsp mayonnaise
- 2 tbsp chopped parsley, 1 tbsp chopped dill, 2 tbsp sliced chives
- 1 tsp Dijon mustard, 1 tsp lemon zest, 1 tsp kosher salt, 1/2 tsp black pepper
- 1/2 cup (60 g) all-purpose flour; 2 large eggs; 1 1/2 cups (75 g) panko breadcrumbs
- Neutral oil for frying (about 4 cups / 950 ml), plus lemon wedges for serving
- Lemon aioli: 1/2 cup (120 g) mayonnaise, 1 small garlic clove, 1 tsp lemon zest, 1 tbsp lemon juice, 1 tsp Dijon, 1/4 tsp kosher salt
Do This
- 1) Boil potatoes until very tender; mash with butter and mayo, then cool 10 minutes.
- 2) Bake fish at 400°F (205°C) for 12–15 minutes; cool and flake.
- 3) Mix potatoes, flaked fish, herbs, Dijon, lemon zest, salt, and pepper; chill 30 minutes.
- 4) Shape into 12 small cylinders or patties; bread with flour, egg, then panko.
- 5) Fry at 350°F (175°C) for 2–3 minutes per side until golden; drain on a rack.
- 6) Stir together lemon aioli ingredients; serve croquettes hot with aioli and lemon.
Why You’ll Love This Recipe
- Crispy outside, fluffy and flaky inside: the best of mashed potatoes and tender fish in one bite.
- Great way to use up leftover cooked fish or mashed potatoes (with simple adjustments).
- The lemon aioli is bright, creamy, and makes the croquettes feel restaurant-worthy.
- Make-ahead friendly: shape and bread them earlier, then fry right before serving.
Grocery List
- Produce: russet potatoes, lemon, garlic, parsley, dill, chives
- Dairy: unsalted butter
- Pantry: mayonnaise, Dijon mustard, all-purpose flour, panko breadcrumbs, kosher salt, black pepper, neutral frying oil
- Seafood: cod (or haddock/pollock)
Full Ingredients
Fish & Potato Croquettes
- 1 lb (450 g) russet potatoes, peeled and cut into 1-inch (2.5 cm) chunks
- 1 lb (450 g) cod fillets (or haddock/pollock), patted dry
- 1/2 tsp kosher salt (for seasoning the fish)
- 1 tbsp olive oil (for baking the fish)
- 2 tbsp (28 g) unsalted butter, melted
- 2 tbsp (30 g) mayonnaise
- 1 tsp Dijon mustard
- 1 tsp finely grated lemon zest
- 2 tbsp finely chopped fresh parsley
- 1 tbsp finely chopped fresh dill
- 2 tbsp thinly sliced chives
- 1 tsp kosher salt (for the mixture)
- 1/2 tsp freshly ground black pepper
Breading Station
- 1/2 cup (60 g) all-purpose flour
- 2 large eggs
- 1 tbsp water
- 1 1/2 cups (75 g) panko breadcrumbs
Lemon Aioli
- 1/2 cup (120 g) mayonnaise
- 1 small garlic clove, finely grated (or crushed to a paste)
- 1 tsp finely grated lemon zest
- 1 tbsp (15 ml) fresh lemon juice
- 1 tsp Dijon mustard
- 1/4 tsp kosher salt
- 1 tbsp water, as needed to thin (optional)
For Frying & Serving
- About 4 cups (950 ml) neutral oil (canola, vegetable, or sunflower), for frying
- Lemon wedges, for serving
- Extra chopped herbs, for garnish (optional)
Step-by-Step Instructions
Step 1: Cook and dry out the potatoes
Place the potatoes in a medium pot and cover with cold water by about 1 inch (2.5 cm). Add a generous pinch of salt. Bring to a boil over high heat, then reduce to a steady simmer.
Cook for 12–15 minutes, or until the potatoes are very tender and a knife slides in easily. Drain thoroughly, then return the potatoes to the hot pot for 1 minute, shaking the pot gently, to steam off excess moisture (this helps the croquettes hold together).
Step 2: Mash until smooth (but don’t overwork)
Mash the hot potatoes until smooth. Add the melted butter and mayonnaise and mash just until combined. Let the mash cool for 10 minutes so it doesn’t melt the fish or turn the mixture gummy.
Step 3: Bake the fish and flake it
Heat the oven to 400°F (205°C). Place the cod on a lined baking sheet, drizzle with 1 tbsp olive oil, and sprinkle with 1/2 tsp kosher salt.
Bake for 12–15 minutes, until the fish is opaque and flakes easily (an instant-read thermometer inserted into the thickest part should read 145°F (63°C)). Cool for 5 minutes, then flake into bite-size pieces with a fork. Try not to shred it too finely; little flakes give the best texture.
Step 4: Mix the croquette base
In a large bowl, combine the mashed potatoes, flaked fish, Dijon mustard, lemon zest, parsley, dill, chives, 1 tsp kosher salt, and 1/2 tsp black pepper.
Fold gently until evenly mixed. You want it cohesive, but still a little chunky with visible pieces of fish.
Step 5: Shape and chill (this makes frying easier)
Line a baking sheet with parchment paper. Divide the mixture into 12 portions (about 2 heaping tablespoons each). Shape into short cylinders or thick patties, about 2 1/2 inches wide and 3/4 inch thick.
Refrigerate uncovered for 30 minutes. Chilling firms them up so they bread cleanly and hold their shape in hot oil.
Step 6: Bread the croquettes
Set up a breading station: place the flour in one shallow bowl. In a second bowl, whisk the eggs with 1 tbsp water. Place the panko in a third bowl.
One at a time, coat each chilled croquette in flour (tap off excess), dip in egg, then coat generously in panko, pressing lightly so the crumbs adhere. Return to the baking sheet.
Step 7: Make the lemon aioli
In a small bowl, stir together 1/2 cup mayonnaise, garlic, lemon zest, lemon juice, Dijon, and salt. If you’d like a looser, more dip-friendly texture, stir in up to 1 tbsp water, a teaspoon at a time.
Cover and refrigerate until serving.
Step 8: Fry until deeply golden and crisp
In a heavy-bottomed pot or deep skillet, heat about 1 1/2 inches of neutral oil (you’ll use roughly 4 cups / 950 ml) to 350°F (175°C). Use a thermometer for accuracy.
Fry in batches of 4–5 croquettes (don’t crowd the pan). Cook for 2–3 minutes per side (about 5–6 minutes total) until crisp and deeply golden. Adjust the heat as needed to keep the oil close to 350°F (175°C).
Transfer to a wire rack set over a baking sheet (or a paper towel-lined plate) and sprinkle with a tiny pinch of salt while hot. Serve immediately with lemon aioli and lemon wedges.
Pro Tips
- Dry potatoes are your friend. Steaming the drained potatoes for 1 minute prevents a wet mixture that falls apart during frying.
- Chill for clean breading. If the mixture feels soft, chill an extra 15 minutes before breading.
- Keep oil temperature steady. If oil drops below 340°F (170°C), croquettes can absorb oil; if it rises above 365°F (185°C), the coating can brown before the center warms through.
- Use a rack, not just paper towels. A rack keeps the coating crisp all the way around.
- Want extra crunch? After breading, chill the croquettes for 10 minutes to help the crumbs set before frying.
Variations
- Salmon croquettes: Swap cod for 1 lb (450 g) cooked salmon (great with leftover roasted salmon). Add 1/4 tsp smoked paprika to the potato mixture.
- Spicy lemon aioli: Add 1 tsp hot sauce or 1/2 tsp cayenne to the aioli.
- Oven option (lighter): Spray breaded croquettes generously with oil spray, bake at 425°F (220°C) for 18–22 minutes, flipping at 10 minutes, until browned and hot throughout.
Storage & Make-Ahead
Refrigerate: Store cooked croquettes in an airtight container for up to 3 days. Re-crisp on a baking sheet at 400°F (205°C) for 10–12 minutes (flip once), or air-fry at 375°F (190°C) for 6–8 minutes.
Make ahead: You can shape and bread the croquettes, then refrigerate (covered) for up to 24 hours before frying. The aioli can be made up to 3 days ahead and kept refrigerated.
Freeze: Freeze breaded (unfried) croquettes on a tray until solid, then bag and freeze for up to 2 months. Fry from frozen at 350°F (175°C) for 7–9 minutes, turning gently, until deeply golden and hot in the center.
Nutrition (per serving)
Approximate, based on 4 servings and including aioli: 690 calories, 29 g protein, 52 g fat, 33 g carbohydrates, 3 g fiber, 980 mg sodium. (Values vary by oil absorption and exact brands.)
