Finely chop the onion and garlic.

Melt the butter in the frying pan over medium heat. Sauté the onion and garlic until softened, about 4 minutes.

Add the 300 g ground beef to the pan. Cook while breaking it apart until no longer pink, about 6 minutes.

Season the beef with salt, black pepper, and sweet paprika. Stir well to distribute the seasonings.

Add the tomato pulp and mustard. Simmer until the mixture is moist but not watery, about 3 minutes.

Stir in the chopped parsley. Remove the pan from the heat.

Add the all-purpose flour to the meat mixture. Mix until it forms a dough that releases from the pan; add a little more flour only if needed.

Transfer the dough to a mixing bowl. Let it cool until safe to handle, about 15 minutes.

Shape the cooled mixture into approximately 16 small balls.

Beat the 2 eggs in one mixing bowl. Place flour and breadcrumbs in separate bowls.

Coat each ball in flour, then beaten egg. Roll each ball in breadcrumbs until fully coated.

Heat the frying oil in the frying pan over medium-high heat. Fry the balls in batches until golden brown, about 3 to 4 minutes per batch.

Lift the croquettes from the oil with a slotted spoon. Drain them on paper towels.

Cool the croquettes for 3 minutes. Serve warm.