Toss the zucchini with the flour.
Heat the olive oil in a pan. Over medium heat, pan fry the zucchini medallions, in a single layer, until the underside is lightly browned. Flip them over and sprinkle with salt and pepper. Continue frying for another minute.
Turn off the heat. Smear each zucchini medallion with tomato sauce. Top with a tomato slice then with a slice of mushroom. Sprinkle with salt and pepper. Return the pan on the stove keeping the heat low this time.
Top each zucchini medallion with a slice of mozzarella. Cover the pan and cook over low heat until the mozzarella is melted.
Using a spoon, scoop out the zucchini medallions and arrange on a plate. Sprinkle with the chopped chili. Serve at once.