Gather all ingredients: grated vegetables, mashed potatoes, minced garlic, chopped herbs, beaten egg, breadcrumbs, flour, and oil.
In a skillet over medium heat, sauté the minced garlic in a tablespoon of oil until fragrant, about 1 minute. Let it cool slightly.
In a large mixing bowl, combine the grated vegetables and mashed potatoes. Add the sautéed garlic and chopped herbs, then pour in the beaten egg. Mix everything thoroughly until well combined and cohesive.
Check the mixture: it should hold its shape when pressed. If too sticky, stir in a little more breadcrumbs; if too dry, add a splash of water or extra egg.
Shape the mixture into small, oval or round croquettes, about 2 inches long, using your hands. Keep them uniform for even frying.
Heat enough oil in a skillet over medium-high heat until it reaches about 180°C (356°F). To test, drop a small piece of bread—if it sizzles immediately and turns golden in 30 seconds, the oil is ready.
Prepare a breading station with flour, beaten egg, and breadcrumbs in separate shallow dishes.
Dredge each croquette in flour, then dip into the beaten egg, allowing excess to drip off. Coat evenly with breadcrumbs, pressing lightly to stick.
Fry the croquettes in batches, about 3–4 minutes each, turning occasionally with tongs until golden brown and crispy. They should crackle when tapped.
Transfer the fried croquettes to a paper towel-lined plate to drain excess oil. Let them rest for 2 minutes to set the crust.
Serve the croquettes hot, garnished with fresh herbs or a squeeze of lemon. Enjoy their crispy exterior and tender, flavorful interior with your favorite dipping sauce.