Place the peeled and cubed potatoes in a pot and cover with cold salted water. Bring to a boil over high heat, then reduce to a simmer and cook until potatoes are very tender, 12–15 minutes. Drain well and return potatoes to the hot pot for 1–2 minutes to evaporate excess moisture.

Mash and cool

Mash the potatoes coarsely with a potato masher or fork until mostly smooth with a few small lumps remaining. Let the mashed potatoes cool until just warm (10 minutes) so they bind well with the salad ingredients without melting the mayonnaise.

Prepare vegetables

While the potatoes cook, finely grate the carrot, dice the red bell pepper, thinly slice the green onions, chop the parsley, and chop the hard-boiled egg if using. Thaw and drain the peas and corn if needed.

Combine salad mix

In a large bowl, combine the warm mashed potatoes, grated carrot, peas, corn, red bell pepper, green onions, parsley, and chopped egg (if using). Add the mayonnaise, Dijon mustard, lemon juice, salt, black pepper, and garlic powder. Mix gently until evenly combined. Taste and adjust seasoning—add more salt, pepper, or lemon juice as desired.

Chill the mixture

Cover the bowl and refrigerate the mixture for at least 30 minutes to firm up. Chilling makes it easier to form uniform croquettes.

Breading & Frying

Shape croquettes

After chilling, scoop about 2.5 tablespoons (roughly golf-ball size) of the salad mixture and shape into a flattened oval or ball. Repeat to make 12–14 croquettes. Place shaped croquettes on a tray lined with parchment and chill for 10 more minutes to help them set.

Set up breading station

Place the flour in a shallow bowl and season with the 0.25 tsp salt and 0.25 tsp pepper. Place the beaten eggs in a second shallow bowl. Place the breadcrumbs in a third shallow bowl.

Bread the croquettes

Working in batches, lightly dredge each croquette in flour, shaking off excess. Dip into the beaten egg, then press into breadcrumbs to coat evenly. For a thicker crust, double-dip: return to the egg and breadcrumbs a second time. Place breaded croquettes on a tray and keep chilled until ready to fry.

Fry until golden

Heat a large skillet over medium heat and add enough neutral oil to come about 1/4 inch up the side (about 1/3–1/2 cup depending on pan size). When the oil is hot (test with a breadcrumb — it should sizzle immediately), fry croquettes in batches without overcrowding the pan. Cook 2–3 minutes per side until golden brown and crisp. Use a spatula to turn gently so they keep their shape. Adjust heat as needed to keep crust from burning while ensuring interior is warmed through.

Drain

Transfer cooked croquettes to a paper towel–lined plate or a wire rack set over a tray to drain excess oil. Keep warm in a 200°F (95°C) oven if making large batches.

Garnish & Serving (optional)

Serve

Arrange mixed salad greens on plates, place 3–4 warm salad croquettes on each bed of greens, and garnish with lemon wedges. Serve with tartar sauce or yogurt-dill sauce on the side for dipping.

Storage

Store any leftover chilled salad mixture in an airtight container in the refrigerator for up to 3 days (do not freeze once mixed with mayonnaise). Cooked croquettes keep refrigerated for 2–3 days; reheat in a 375°F (190°C) oven for 10–12 minutes to crisp, or shallow-fry briefly to re-crisp.