Place potato chunks in a pot and cover with cold salted water.
Bring to a boil, then reduce the heat to a simmer. Cook until tender, about 15–20 minutes.
Drain well and return to the pot. Mash until smooth, then let cool slightly.
Prepare the Flavor Base
In a small skillet, heat 1 teaspoon olive oil over medium heat.
Sauté minced onion and garlic until fragrant and translucent, about 2–3 minutes. Remove from heat and let cool.
Mix the Crocchette Filling
In a large bowl, combine mashed potatoes, flaked tuna, sautéed onion and garlic, parsley, lemon zest, crushed red pepper (if using), Parmigiano-Reggiano, salt, and pepper.
Mix gently until evenly combined. Taste and adjust seasoning.
Shape the Crocchette
Take about 2 tablespoons of the mixture and shape into small cylinders or oval patties.
Place them on a tray lined with parchment paper.
Bread the Crocchette
Beat the egg in a shallow bowl. Place breadcrumbs in another shallow dish.
Dip each crocchetta first in the egg, then coat evenly with breadcrumbs.
Place back on the tray, and repeat with all crocchette.
Fry Until Golden
Heat 1/4 inch of olive oil in a skillet over medium heat.
Fry crocchette in batches, 2–3 minutes per side, until golden brown and crispy.
Transfer to a plate lined with paper towels to drain excess oil.
Serve
Serve warm, garnished with a sprinkle of parsley and a wedge of lemon.
Optional: drizzle lightly with extra-virgin olive oil, or serve with a garlic aioli for dipping.
Notes
Tips
For a lighter version, bake the crocchette at 400°F (200°C) for 20 minutes, flipping halfway, instead of frying.Mix a teaspoon of capers or finely chopped sun-dried tomatoes into the filling for an extra punch.Use panko breadcrumbs for extra crunch and texture.