Start by peeling the skin and removing the pit of the avocado. You can use a potato masher to make your avocados chunky. You can also just slice them into small cubes but you don't want them to be too mashed up.
Dice the roma tomato, and onion into small chunks. Place the onion in water to take some of the bite out. Add them to the diced avocado. Add the jalepeno to taste. Mix together.
Add the lemon juice, cilantro, and salt to taste. You can add more of the ingredients to your taste and liking.