Cut bottom stems off collard greens up to the leaves. Stack 3 to 4 leaves. Roll leaves and cut crossways in 1/2-inch strips. Continue process until all leaves are cut. Wash cut leaves thoroughly. Add vegetable oil to large heavy pot. Once oil is hot add 1/2 cup minced onions, 1/2 cup carrots, and all 4 pieces of smoked turkey wing. Saute about two minutes. Add washed greens and chicken stock. Cover pot and cook for about 1 hour and 45 minutes, or until greens are tender. Once greens are tender, remove pot from stove. Add vinegar and sugar to collard greens. Stir greens. Let greens stand two minutes before serving. Garnish with remaining minced onions and diced tomatoes.