Mix the garlic paste in a bowl with the ground annato seeds. Blend in 2 tablespoons of the olive oil until smooth paste is formed. Add the 1/2 teaspoon of salt. Spread the paste evenly over the skirt steaks, making sure that all sides are painted. Marinate the steaks and refrigerate for at least 8 hours.
Place the remaining tablespoon of olive oil in a very large, heavy saucepan or heavy dutch oven. Over medium high heat, add the minced onion and the chopped green pepper. Saute for about 5 minutes, stirring, or until the onions and peppers are just starting to brown. Turn heat to low. Add the ground cumin and stir well. Saute for 1 minute. Turn heat to high and add the black turtle beans. Stir well. Add 3 cups of water and bring to the boil as quickly as possible. Reduce heat to a very slow simmer and cook, partially covered, until the black beans are just tender. This will take no more than an hour and 15 minutes. Strain the beans, reserving both the beans and the bean stock. Season the bean stock with salt and pepper; you should have about 1 cup.
When ready to serve, prepare a hot charcoal fire. Place the skirt steaks on the fire and cook, turning once, until crusty on the outside, rare on the inside (about 6 minutes). Alternatively, you could sear the steaks in a heavy, cast-iron skillet that has been heated for 10 minutes over very high heat. When steaks are done, using a very sharp knife, cut each steak horizontally, leaving the steaks attached along one long side (this is like butterflying them).
Stuff the steaks: Lay out 2 tablespoons of finely chopped parsley along one flap of each steak. Pit and halve the olives and lay out 4 olives over the parsley on each steak. Sprinkle with the dried oregano. Finally, divide the shredded lettuce among the four steaks, placing the shreds over the olives and parsley. Cover the stuffing with the upper flap of skirt steak.
With a cheese cutter, cut the Monterey Jack into 24 thin strips, each one about 1 1/2" by 4". Overlap 6 slices of the cheese over each stuffed skirt steak, placing the long side of the cheese perpendicular to the long side of the steak. Place each steak on an oven-proof dinner plate and place the plates under a broiler for about 30 seconds, or until the cheese has melted.
Finish the sauce: In a clean saucepan, melt the butter over medium-high heat. Add the flour and cook for 2 minutes, stirring, until the roux has begun to darken. Add 1 cup of the reserved bean stock, stirring well to blend. Bring to the boil and add 2 tablespoons of the reserved black beans (serve the rest of the beans as a side dish, or reserve for another use). Season well with salt and pepper.
Divide the sauce among the four dinner plates; each plate should have sauce on two sides of the steak. Garnish the melted cheese and the sauce with a little finely chopped parsley.