Pisto Manchego with manchego cheese

Peel the onion, remove the seeds to the peppers, clean the leek and zucchini skin. Wash them and cut them into small pieces. Put olive oil in a frying pan and add the onion and leek. Fry the onion and the leek lightly and add the green and red pepper. Sauté all together. Add the zucchini to the pan a few minuts and then pour the crushed tomato and a little pinch of sugar and let it simmer until the tomato is fried and the vegetables are tender. Try the pisto and add salt if necessary. When the pisto is ready, let it cool a little and then cut small sliches of manchego cheese and add it to the plate.