Finely chop onion, cilantro, and jalapenos (remove seeds).
Mix together onions, cilantro, jalapenos and salt, and mash with back of spoon until smooth and juicy.
Add avocado chunks and mash slightly (should still be kinda chunky)...i use potato masher. Squeeze lemon wedge over avocado before mashing.
Chop tomato, stir into avocado mixture (seeds and all). Add more chopped cilantro for garnish; also add a little more salt to taste.