1) Place all dough ingredients in the bucket of your bread machine and program for the dough cycle. Or make the dough using a stand mixer, or your hands: mix, knead, and let rise till puffy.
2)Wash and trim the asparagus, removing any woody stems. Toss the spears and the onion pieces with garlic or olive oil. On a preheated grill or in a 350°F oven, grill or roast the vegetables until they are just tender and browned. The tips of the spears and onion pieces will be caramelized. Remove from the heat, add salt and pepper to taste, and set aside to cool slightly.
3) Take the risen dough and roll it out to a 10" x 15" rectangle. Spread the shredded cheese on the dough, leaving a 1" border all around. Add the grilled veggies in an even layer.
4) Beginning on one of the 15" sides, roll the dough up as you would a jelly roll or cinnamon buns. Seal the ends and seams well, and place on a parchment-lined sheet pan. Rub the surface well with garlic or olive oil, and cover with plastic wrap. Rise the stromboli for 30-45 minutes or until quite puffy.
5) Bake the stromboli in a preheated 400°F oven until deep golden brown. Cool for 5-10 minutes before slicing and serving with marinara for dipping.
Yield: one large stromboli, about 14 servings.