In a large, non-stick skillet over medium - high heat, melt one tablespoon of the butter. Add the shaved steak and cook, stirring often, until no longer pink. Remove the steak from the pan, leaving behind the juices.
Over medium heat, add a second tablespoon of butter and melt. Add the garlic and cook, stirring often, until fragrant, about one minute.
Add the tomato paste, chili powder, sugar, smoked paprika, red pepper flakes and salt. Cook, stirring often, for an additional minute.
Stir in the beer and cook for a couple of minutes until smooth. Return the steak to the pan with the sauce and stir to combine and cook for a few minutes until heated through.
Remove the steak for the pan, leaving the juices behind. Add the onions and peppers. Cook over medium heat, stirring often, until they are softened, about 6 - 8 minutes.
Remove the peppers and onions. Add a bit of butter to the skillet and place a flour tortilla in the skillet on top of the melted butter. Layer half the tortilla with cheese, steak, peppers and onions and sliced jalapeños. Fold the tortilla in half. Grill on both sides until cheese is melted. Repeat with all four tortillas.