Turn crockpot to high and set aside. In a large, nonstick skillet, brown ground beef over medium-high heat. While meat is browning, grate onion, carrot, zucchini, and yellow squash using a food processor {or you can do it by hand}. Drain well and spoon meat into warmed crockpot. Sprinkle with salt and pepper.
Replace pan to the heat.
Place vegetables into the hot pan and sprinkle with salt and pepper. Saute until the water from the veggies has evaporated and vegetables are tender about 7 minutes. Pour over meat in crockpot.
Replace pan back on the heat. Pour in all ingredients for the sauce and whisk until smooth. Simmer gently 5 minutes, then pour over ingredients in crockpot. Stir to coat everything evenly. Cover and cook 3-4 hours, stirring occasionally. Serve over tightly toasted whole wheat hamburger or kaiser buns.