1. Bring beef, 2 cups water, and 1 1/4 teaspoons salt to boil in 12-inch nonstick skillet over medium-high heat. Reduce heat to low, cover, and gently simmer until beef is very tender, about 1 hour 45 minutes. (Check beef every 30 minutes, adding water so that bottom third of beef is submerged.) While beef simmers, combine garlic, oil, and cumin in bowl. Combine orange juice and lime zest and juice in second bowl.

2. Remove lid from skillet, increase heat to medium, and simmer until water evaporates and beef starts to sizzle, 3 to 8 minutes. Using slotted spoon, transfer beef to rimmed baking sheet. Pour off and reserve fat from skillet. Rinse skillet clean and dry with paper towels. Place sheet of aluminum foil over beef and, using meat pounder or heavy sauté pan, pound to flatten beef into 1/8-inch-thick pieces, discarding any large pieces of fat or connective tissue. (Some of beef should separate into shreds. Larger pieces that do not separate can be torn in half.)

3. Heat 1 1/2 teaspoons reserved fat in now-empty skillet over high heat. When fat begins to sizzle, add onion and 1/4 teaspoon salt. Cook, stirring occasionally, until onion is golden brown and charred in spots, 5 to 8 minutes. Add sherry and 1/4 cup water and cook until liquid evaporates, about 2 minutes. Transfer onion to bowl. Return skillet to high heat, add 1 1/2 teaspoons reserved fat, and heat until it begins to sizzle. Add beef and cook, stirring frequently, until dark golden brown and crusty, 2 to 4 minutes.

4. Reduce heat to low and push beef to sides of skillet. Add garlic mixture to center and cook, stirring frequently, until fragrant and golden brown, about 30 seconds. Remove pan from heat, add orange juice mixture and onion, and toss to combine. Season with pepper to taste. Serve immediately with lime wedges.

Serves 4 to 6