Prepare all ingredients by chopping vegetables and gathering staples.

Sauté the chopped broccoli, zucchini, bell pepper, and mushrooms in a pan.

Add cooked rice to the sautéed vegetables and mix well.

Add ketchup to the mixture and stir until evenly coated.

Form the mixture into small balls, inserting mozzarella cheese in the center of each ball.

Coat each ball in flour, then dip in beaten egg, and finally roll in breadcrumbs.

Heat oil in a pan and fry the croquettes until golden brown.