Slice potatoes and arrange on bottom of large pot. Add sliced tomato, bell pepper, and garlic. Cover with about 1/2 cup of water and melt the veggies down to a sauce. Add fish and cover with spice/oil/salt mixture. Top with chopped cilantro and cook on high uncovered for 20 minutes. Lower heat and simmer, covered for another 30 minutes. While fish is cooking, tilt pot and spoon sauce over the filets periodically.