Wash fennel. Trim off feathery leaves. If desired, chop enough of the leaves to equal 2 tablespoons; set aside. Trim fennel bulb. Chop enough of the bulb to make 1 cup. Cut remaining bulb into strips to use for dippers.
In a medium bowl combine chopped fennel, onion dip, red onion, and green onion. Serve immediately or cover and chill in the refrigerator up to 24 hours. (If chilling dip, wrap and chill fennel leaves, if using.) To serve, spoon dip into serving bowl. If desired, sprinkle top with fennel leaves, snipped lemon thyme, and/or snipped chives. Serve with vegetable dippers. Makes about 2-1/4 cups dip.