1. Grill sausage and vegetables on a greased medium-hot grill or stovetop grill, turning occasionally, until nicely charred and heated through (about 8 to 10 minutes).

2. As sausages and vegetables are cooking, slit the baguette sections, unfold and hollow-out some of the interior bread. Spread the rolls with pesto, and layer each roll with a quarter of the mozzarella.

3. Transfer the onions and pepper to the rolls, place a sausage on each roll, and serve.