Halve avocados lengthwise; remove pits and peel. Mash avacado in bowel with potato masher. Add onion, chili pepper, vinegar and salt; mix well. Place in plastic freezer container and cover lightly and freeze. To serve, let thaw; finely chop tomato; stir into avacado mixture. Serve with raw vegetables, cooked shrimp or chips. Note: excellent fresh and good after frozen.