Heat oil and butter in a frying pan. Add garlic and onions and saute. Add chiles, chile juice, carrots, tomatoes, parsley and cilantro. Season with salt and pepper and cook over low heat until mixture thickens, about 25 minutes. Add crab meat and saute until mixture thickens. Correct seasonings. To serve, place crab on a platter. Serve with freshly made tortillas to roll into tacos. Variation: The shredded crab may also be served in crab shells, sprinkled with bread crumbs, melted butter and parsley and baked in a hot oven for 25 minutes.