Step 1Heat the grill or a stovetop grill pan over high heat.
Step 2Combine the soy sauce, hoisin sauce, lemon juice, garlic, ginger and brown sugar in a bowl. Coat both sides of the steak with 1/4 cup of the marinade and place the rest in a serving bowl.
Step 3Grill the steak until medium-rare or until it reaches an internal temperature of 140 degrees, about 5 minutes each side. Let rest for a few minutes, then slice the steak into very thin pieces.
Step 4Heat the oil in a large skillet over medium-high heat. Cook the bell peppers and onions until soft and the green onions start to turn golden, about 5 minutes. Remove from the heat and place on a serving plate.
Step 5Place the pancakes on the grill. Turn after they've puffed, about 1 minute, and cook until the pancakes soften and show golden grill marks. (If you over-grill them, they will dry out and crack when rolling.) Stack the pancakes on a serving plate.
Step 6At the table, have each person brush the surface of a pancake with the reserved marinade, then place several strips of steak so that they overlap down the center of the pancake. Spread the bell peppers and green onions on top, followed by a handful of pea sprouts so that they hang out the ends. Tightly roll up the pancake and cut in half on the diagonal. Any remaining marinade can be used as a dipping sauce.