Chop tomato very fine in wooden bowl;add pulp from avocado, and mash with silver fork or wooden spoon.
Blend in remaining ingredients; mix thoroughly.
As a dip, serve in bowl surrounded with crisp crackers or raw vegetables.
For salad dressing, increase lemon juice to 3 tablespoons, and omit chili powder.
If made some time before using, spread thin layer of mayonnaise over top of mixture to prevent discoloration (a tendency of peeled avocado).