For the Brine:

In a medium saucepan, bring 1 kilogram water to a boil. Add salt and sugar and stir until fully dissolved.

Remove from heat and add all remaining ingredients. Let cool to room temperature.

For the Lamb:

Place lamb in a large container. Submerge in Brine. Cover and refrigerate 12 hours.

For the Adobo Marinade:

In a blender, purée all ingredients and 500 grams water. Set aside.

For the Lamb Barbacoa:

Remove American lamb from Brine. Transfer to a nonreactive container. Coat with Adobo Marinade. Cover and refrigerate 8 hours.

To Assemble and Serve:

Heat oven to 250°F. Remove Lamb Barbacoa from Adobo Marinade, reserving excess Adobo Marinade separately. In a cast iron skillet over medium-high flame, heat oil. Add Lamb Barbacoa and sear on all sides. Transfer seared Lamb Barbacoa to a hotel pan.

Add enough water to fill the pan halfway. Add reserved Adobo Marinade. Top with banana leaves. Cover pan with aluminum foil and roast 1 hour. Reduce heat to 180°F and cook additional 90 minutes, or until meat is tender and begins to fall off the bone. Let cool. In a shallow serving bowl, spoon black beans.

Top with Lamb Barbacoa. Spoon excess Adobo Marinade onto the beans. Garnish with cilantro and white onion.