For the steak: Scatter half of the garlic pieces, half of the orange slices and half of the onion slices on the bottom of a glass dish large enough to hold the flank steak. Sprinkle the flank steak all over with salt and pepper and place in the prepared dish. Scatter the remaining garlic, orange and onion over the flank steak and pour the beer and soy sauce over it. Cover with plastic wrap and marinate 1 hour at room temperature or overnight in the fridge.
Prepare a grill for medium-high heat or preheat the broiler.
For the soy-lime sauce: Mix the soy sauce, lime juice, cilantro, chiles and green onions in a small bowl.
Remove the meat from the marinade and discard the marinade. Grill the steak to the desired doneness, about 4 minutes per side for medium rare. Transfer to a cutting board and cut crosswise into strips.
Make tacos using slices of flank steak and the jicama slices as tortillas. Drizzle with the soy-lime sauce and serve.