Make the filling

1. Heat the oil in a skillet. Cook onion and bell pepper until softened, about 5 to 7 minutes. Add garlic, paprika, and cumin; cook 30 seconds.
2. Add the chopped corned beef and potato. Stir in the Dijon and parsley. Add a spoonful of stock only if it seems dry. Season with black pepper, then cool completely.
3. The filling should be fairly dry, not wet, or the plantain dough gets harder to handle.

Cook the plantains

1. Peel the green plantains and cut into thick chunks. Boil in salted water until very tender, about 15 to 20 minutes.
2. Drain well, then let excess moisture steam off for a minute or two.

Make the dough

1. Mash the hot plantains thoroughly with the butter or olive oil and salt. Add the optional egg if using.
2. Then add flour or masa harina a little at a time until you get a dough that is soft, cohesive, not sticky, and easy to pat into a disk without cracking badly
3. Usually 1/4 cup is enough, sometimes a little more if the plantains were wet.
4. Let it cool until comfortable to handle.

Form the empanadas

1. Divide dough into 10 to 12 balls.
2. Place each ball between parchment or plastic wrap and press into a round about 4 to 5 inches across. They do not need to be ultra-thin; plantain dough is usually thicker than wheat dough.
3. Put 1 to 2 tablespoons filling on one half. Fold over using the parchment/plastic to help, then press edges closed. If the edges crack a bit, patch them with your fingers.
4. This dough is more rustic than pie-crust dough, so don’t worry if they look handmade.

Cooking options:

1. Best option: fry
2. Heat about 1 to 1 1/2 inches of neutral oil to 350°F.
3. Fry 2 to 3 at a time until golden, about 3 to 4 minutes per side depending on thickness. Drain on paper towels.
4. This is the method I’d choose. Plantain dough usually fries better than it bakes.
5. Baking option:
6. Brush with egg wash and bake at 400°F for about 20 to 25 minutes.
7. This works, but the texture will be less crisp and a little denser than fried.