Whirl all ingredients except olive oil and bread in a blender or food processor.
Pour 1/2 tablespoon olive oil into a 10- to 12-inch nonstick frying pan over medium-high heat. When hot, drop about 3/4 cup tofu mixture into pan. Spread into a patty about 4 inches wide and 1 inch thick. Repeat to form two more patties in pan.
Lower heat to medium and cook, turning once, until well browned on both sides and firm to the touch, 10 to 12 minutes total. Transfer patties to a pan in a 200° oven. Add remaining oil to pan and cook remaining patties.
Serve burgers between slices of toasted bread (see note, above).