In a medium-size bowl, mortar or a Mexican molcajete, mash 1 tablespoon onion with the chile, 1/2 teaspoon cilantro, and 1/2 teaspoon salt to make a paste.
STEP 2
Cut the tomato in half, squeeze out juice and seeds. Chop pulp, and add it to the bowl.
STEP 3
Cut the avocado in half lengthwise, around the pit. Twist top half to separate and remove the pit. Slice avocado flesh into a grid. Scoop the avocado into the bowl.
STEP 4
Add remaining onion and cilantro. Gently fold ingredients together. Season with more chile and salt if desired. Serve at once with tortilla chips.