Preheat oven to 375F. Line a cookie sheet with parchment paper, or spray with nonstick spray.
Place everything except the breadcrumbs in the bowl of a food processor and blend until almost smooth and only small flecks of vegetables remain. Sprinkle with the breadcrumbs and pulse to combine; check the texture of the mixture with your hands. It should be very moist but still hold together. If the mixture is too wet, add more breadcrumbs until desired consistency is reached.
Shape the mixture into 4 burgers. Flatten each burger to 1/2 inch thickness and place on the cookie sheet.
Bake about 15 minutes on one side, then flip and bake another 10 minutes on the other side, until burgers are lightly browned. Serve in buns with desired condiments.
*This recipe has been tested using leftover pulp from juicing with the new Fagor Slow Juicer.