1. Sauté onions in 3 Tbsp. hot oil in a 3-qt. saucepan over medium-high heat 4 minutes. Add garlic; sauté 1 minute. Stir in peas, next 4 ingredients, 3 1/2 cups water, and 2 Tbsp. adobo sauce from canned chipotle peppers. (Reserve peppers for another use.) Bring to a boil; cover and reduce heat to medium. Simmer, stirring occasionally, 1 1/2 hours. Uncover and cook, stirring occasionally, 20 to 30 minutes or until peas are tender. Discard bay leaf. Remove hocks. Remove ham from bones; discard bones. Chop ham; stir into peas. Add salt to taste; cover and keep warm over low heat.
2. Stir together 3/4 cup flour, 1/2 tsp. salt, and 1/2 tsp. pepper in a shallow dish. Whisk together cornmeal, ground chipotle chile, and remaining 3/4 cup flour, 1/2 tsp. salt, and 1/2 tsp. pepper in a second shallow dish. Whisk together eggs and buttermilk in a third shallow dish.
3. Dredge green tomatoes, 1 slice at a time, in flour mixture, shaking off excess. Dip in egg mixture, and dredge in cornmeal mixture.
4. Pour oil to depth of 1 inch in a cast-iron skillet. Heat over medium-high heat to 375°. Fry green tomato slices, in batches, in hot oil 3 minutes on each side or until crisp. Drain on a wire rack over paper towels. (Let oil temperature return to 375° between batches.)
5. Divide peas among 6 plates. Top each with 1 red tomato slice and 1 fried green tomato slice. Repeat tomato layers once. Sprinkle cheese and cilantro over tomatoes. Serve with hot sauce.