Combine garlic, jalapeño, cumin, coriander, cayenne, black pepper, salt, sugar and water in food processor and blend until smooth. Combine blended mixture with diced onion and beer to create a brine. Marinate steak for 2 hours. Remove steak from brine, coat with oil and grill. Let beef rest 5 min and slice into strips. Combine romaine, cilantro, lime juice and tomato. Plate steak atop heated corn tortilla along with lettuce mixture and cheese.
Tip: Traditionally, small corn tortillas are heated in hot oil for a few seconds or steamed and served immediately.