In a large salad bowl, combine the radicchio, spinach leaves and lettuce. Drizzle a little olive oil and balsamic vinegar over the salad, salt to taste and gently toss.
Place flour on a flat plate and breadcrumbs on another. In a small bowl, lightly beat the egg. Drain mozzarella balls and place them on the plate with the flour. Coat evenly each ball, then transfer it to the egg bowl. Coat evenly with the egg, then place on the breadcrumbs and coat evenly. Press breadcrumbs into the balls to ensure it sticks well. Repeat with all the mozzarella balls.
Heat frying oil in a pan. When the oil is hot enough, place breaded mozzarella balls in the oil carefully and fry for about 2 minutes, gently turning as they brown. Fry until golden brown, then remove from the pan and place to drain on paper towels.
Add warm fried mozzarella to the salad and top with some crushed tortilla chips. Serve.