Spicy Jerk Vegetables with Yogurt-Scallion Sauce

1 tablespoon(s) onion powder

1 teaspoon(s) freshly ground nutmeg

1 teaspoon(s) dried powdered ginger

1 teaspoon(s) garlic powder

1/2 teaspoon(s) cayenne or ground dried habanero

1 1/20 tablespoon(s) dried thyme

Kosher salt

Freshly ground pepper

1 3/4 cup(s) extra-virgin olive oil

3 large portobello mushrooms , gills scraped out with a spoon, mushrooms thickly sliced

1 pound(s) oyster mushrooms , thickly sliced

1/2 pound(s) shiitake mushrooms , stemmed

1 fennel bulb , sliced

1/4 inch thick through the core

2 red bell peppers , quartered

1 1/20 pound(s) (thin) eggplant , sliced

1 pound(s) (medium) asparagus

8 whole(s) scallions

1/2 cup(s) minced scallions

1 large sweet onion , sliced

1/2 inch thick

2 cup(s) plain fat-free Greek yogurt

1/4 cup(s) freshly squeezed lime juice

Grilled bread , for serving