Directions. 1  Puree the avocado in a blender or food processor with the sour cream, mayonnaise, lemon juice, garlic, salt and pepper. 2  Place in serving bowl. 3  This is a tip I found for keeping the dip from darkening.4  Spread a layer of sour cream over the top of the avocado dip and seal it to the sides of the serving dish.irections. 1  Puree the avocado in a blender or food processor with the sour cream, mayonnaise, lemon juice, garlic, salt and pepper. 2  Place in serving bowl. 3  This is a tip I found for keeping the dip from darkening.