Green Avocado Hummus

This is a delicious and unusual hummus recipe that comes courtesy of Linda McCartney (with a few changes). She notes that adding a few chopped fresh spinach leaves will enhance the green color.

1 (16 ounce) can garbanzo beans, drained, rinsed
1-1/2 teaspoons tahini
1/2 lemon, juice of
2 tablespoons sour cream
1-1/2 tablespoons olive oil