Peel tomatoes by placing in a bowl and pouring boiling water over them. Pour off water after 10 seconds and peel off skins. Slice tomatoes into a bowl and sprinkle with chopped coriander. If using chili, cut off stalk, slit open and remove seeds. Take care that you do not put fingers near eyes or mouth. Chop chili finely. Otherwise use plenty of black pepper. Combine chopped chili or pepper with lemon juice and about 1 teaspoon salt. Beat in 1/4 cup olive oil. Pour over tomatoes and leave for 15 minutes before serving.