Spicy Jerk Vegetables with Yogurt-Scallion Sauce

1 tablespoon ground allspice

1 tablespoon onion powder

1 teaspoon freshly ground nutmeg

1 teaspoon dried powdered ginger

1 teaspoon garlic powder

1/2 teaspoon cayenne or ground dried habanero

1 1/2 tablespoons dried thyme

Kosher salt

Freshly ground pepper

1 3/4 cups extra-virgin olive oil

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

1 pound oyster mushrooms, thickly sliced

1/2 pound shiitake mushrooms, stemmed

1 fennel bulb, sliced 1/4 inch thick through the core

2 red bell peppers, quartered

1 1/2 pounds thin eggplant, sliced 1/2 inch thick

1 pound medium asparagus

8 whole scallions, plus 1/2 cup minced scallions

1 large sweet onion, sliced 1/2 inch thick

2 cups plain fat-free Greek yogurt

1/4 cup fresh lime juice

Grilled bread, for serving