Cook the jalape¤os in boiling water for about 5 minutes or until soft. When jalape¤os are cooked (soft) drain and purée in blender with onion (cut in quarter parts), garlic clove and cilantro. Pour into large container and mix in crushed tomatoes and salt.
Remember: Salsa is always made to your indiviual taste. Use more crushed tomatoes to make it mild: use less to make it hot. The onion is what gives the salsa most of its flavor but you can use more garlic if you wish. Play with the ingredients until you find the taste you like the best.