Sprinkle the flank steak liberally with salt, place in a resalable gallon sized plastic bag, or in a large container with an air-tight lid.
Stir together the Worcestershire sauce, soy sauce, balsamic vinegar, 2 tablespoons honey and ½ cup stout beer. Pour the mixture over the steak, seal (remove as much air as you can from the bag, if using), and refrigerate for 12-24 hours.
In a small bowl stir together the remaining honey and stout beer, warm slightly if the mixture is having a difficult time coming together, set aside.
Remove the steak from the marinade, pat dry.
Preheat the grill to medium high.
Cut the peppers into slices, making sure they are too large to fall between the grates in your grill (you can always slice them thinner after grilling).
Brush the steak on all sides with honey glaze before adding to the grill. Grill for 3-5 minutes on each side before turning, re-brushing with glaze every time you flip the steak. Grill until the internal temperate of the steak reaches 135F, remove from grill and allow to rest for 5 minutes. Grill the peppers until softened, about 4 minutes.
Serve steak and peppers along side butter lettuce leaves, green onions and sriracha sauce, allow guests to assemble as desired.