Peel and quarter avocados, reserving pits. Coarsely mash avocado with a fork in a nonmetallic bowl. Set aside any that might be too hard to mash easily.
Pour grapefrit and lime juice into blender. Add shallot and 2 sprigs each of parsley and cilantro. Blen on high until liquified. Add blende mixture to mashed avocado, mix gently. Add remaining vegetables,basil and thyme. Stir well. Garnish with reserved cilantro and parsley. If not serving immediately, place in a small bowl with avocado pits,cover and refrigerate. The avocado pits keep the mixture from turning brown.
Source: Women's Day, Meals in Minutes, August 1990.