Mix refried beans or black beans with salsa in small bowl. Spoon into 10-inch (25 cm) circle on 12-inch (30 cm) platter.

Spoon sour cream over beans, leaving about 1-inch (2.5 cm) border of beans around edge. Spread guacamole over sour cream, leaving border of sour cream showing.

Sprinkle with cheese, tomato and onions over guacamole. Serve immediately, or cover with plastic wrap and refrigerate up to 6 hours. Serve with tortilla chips if desired.