Select Haas avocados that just give slightly to the touch. Insert knife lengthwise and run all the way around the avocado. Twist the two halves apart. Remove the pit by tapping the knife into it and twisting it out, then knock it off the knife. (Be careful, the pit is slippery.) Scoop out the meat of the avocado halves with a large spoon and place in a large, shallow bowl. Mash with a potato masher or with a fork.
Add the juice of half of a lemon, the onion, mayo, a few drops of Tabasco or to taste, 3 or 4 shakes from the cumin bottle, and salt if wanted. Do not over-salt, remember there is salt on the chips. Mix all together, top with a sprinkle of green onion, and tomato when in season. Serve with your favorite tortilla chips,or as a salad topping.
All of the ingredient amounts can be adjusted to taste, and of course up or down depending on the number of avocados. I like a lot of lemon. The onion may be chopped finely or not, as you desire. I do not add salt, there is enough for my family on the tortilla chips. Sour cream or plain yogurt may be substituted for the mayo, but it loses some of the flavor and creaminess. Some may also like to add a little chopped fresh jalapeno.