In bowl, stir together refried beans, 1/4 cup of the sour cream, cumin, 1/4 tsp of the salt and hot pepper sauce; spread in 12-inch round serving dish that is at least 1 1/2 inches deep.
Peel and pit avocados. In bowl, mash together avocados, onion, lime juice, hot pepper flakes, 1/4 cup of the remaining sour cream and remaining salt; spread over refried bean layer. Top with remaining sour cream.
Starting at outer edge, garnish with concentric rings of cheese, tomatoes, green onions and olives. (Make-ahead: Cover and refrigerate for up to 24 hours.)