Heat oven to 325°F. Place onion, red pepper, carrots and celery into food processor and pulse until vegetables are finely chopped.
Heat oil in non-stick skillet over medium-high heat. Add chopped vegetables and cumin to skillet. Cook, stirring often, until softened and any liquid has evaporated. Add bouillon paste or cubes, and stir until completely dissolved. Remove from heat and cool 10 minutes.
While vegetables cool, place ground beef in bowl with bread crumbs, tomato sauce, egg, tomato paste and Worcestershire sauce. Add cooled vegetables to bowl and mix to combine well.
Shape mixture into 2 loaves about 8 inches long and 4 inches wide. Place in glass baking dish and bake 1 hour (until internal temperature is 160°F). Remove, cool about 5 minutes. Slice and serve.