Combine:

1 c. mashed ripe avocado
1 tbsp. lemon juice
1 tbsp. grated onion
1 tsp. salt
1/4 tsp. chili powder (more if you desire)

Spread top with 1/3 cup mayonnaise or salad dressing, sealing to edges of bowl; chill. At serving time stir in mayonnaise and sprinkle with crumbled bacon if desired.