2 red bell peppers
1 tablespoon extra-virgin olive oil, plus more for liberal drizzling
2 medium sweet onions, sliced into wedges, root end attached
1 bulb fennel, thinly sliced, fennel fronds reserved for garnish
3 to 4 large cloves garlic, thinly sliced
Salt and freshly ground black pepper
1 tablespoon white balsamic vinegar
12 small bone-in chicken thighs
Fennel pollen or ground fennel, for sprinkling
1 lemon, zested and juiced