To make Tex-Mex seven-layer dip, spread 1 16-ounce can of refried beans to cover the bottom of a large serving dish. Top the beans with a layer of 1 cup of fresh or prepared guacamole. In a separate bowl, combine 1/4 cup of mayonnaise, 1 8-ounce container of sour cream and 1 1-ounce packet of taco seasoning mix. Spread this mixture over the guacamole.
Shred 2 cups of cheddar cheese, and sprinkle it evenly over the sour cream mixture. Clean and chop 1 whole tomato and 1/4 cup of green onions. Spread these over the cheese, first with a layer of tomatoes and then an even layer of green onions. Drain 1/4 cup of black olives, and sprinkle them over the top. Serve the dip with tortilla chips.
To make guacamole for the second layer, peel 3 avocados, and remove their pits. Mash them together in a bowl with the juice of 1 lime and 1 teaspoon of salt. Dice 1/2 cup of onions and 2 Roma tomatoes. Mince 1 teaspoon of garlic, and chop 3 tablespoons of chopped fresh cilantro. Combine all the ingredients in the bowl with a pinch of ground cayenne pepper, stirring until all the ingredients are evenly incorporated.