1 lg. ripe avocado
1 ripe tomato, finely chopped
1/2 green pepper, seeded & finely chopped
2 tbsp. grated onion
1/2 tsp. chili powder
1/2 tsp. olive oil
1/2 tsp. lime juice
Pepper to taste
Mayonnaise as necessary

Mash avocado with a fork. Add remaining ingredients and blend well.

Use a silver (!) fork to keep avocado from darkening. Before mixing in mayonnaise, spread a thin layer of mayonnaise on top and cover tightly to keep guacamole from darkening.

I usually add extra tomato for additional color contrast (and, cause I like tomatoes!).