Preheat oven (electric cooker: 225 °C/circulating air: 200 °C/gas: see manufacturer). Line a tray with baking paper. Wash the tomatoes. Cut tomatoes and pepperoni into slices. Tear mozzarella finely. Put 2 wheat flat cakes on a baking tray.
Spread the mozzarella, tomatoes and pepperoni over it. Place the remaining flat cakes on top. Bake in a hot oven for 5-7 minutes.
Wash the coriander and pluck the leaves. Cut avocados in half, remove seeds. Remove the flesh from the skin, puree with lime juice and coriander. Season with salt and pepper. Quarter the quesadillas. Add guacamole.