1. Preheat grill. Line a baking sheet with foil. Place onion slices, pepper halves, and mushrooms on the sheet and spray with cooking spray. Turn vegetables and spray second side. Place onions on grill, pepper halves skin-side down, and mushrooms cap-side down. Grill mushrooms and onions until grill marks appear, then turn, about 5 minutes per side for the mushrooms and 6 to 7 minutes per side for the onions. Peppers should be tender, with charred skin, after about 8 to 10 minutes (no need to turn them). When vegetables are done, transfer them to the baking sheet.

2. While vegetables are cooking, heat the taco shells according to package instructions in a conventional oven or microwave. Transfer refried beans to a medium bowl and heat in the microwave until warmed through, about 2 minutes.

3. Peel charred skin from the pepper halves. Cut pepper into 1/4-inch-wide slices and transfer to a large bowl. Cut onions and mushrooms into 1/4-inch slices and add to the bowl. Pour any juices that may have accumulated on the baking sheet into the bowl. Sprinkle salt, cumin, and thyme over the vegetables. Add vinegar and stir well to distribute the seasonings.

4. Assemble the tacos. Gently spread a scant 1 1/2 tablespoons refried beans inside one side of each taco shell. Place about 1/4 cup arugula or spinach in bottom of shell, then top with onion-mushroom mixture. Sprinkle with 2 tablespoons cheese. Serve immediately, with salsa on the side if desired

Source: Hannaford fresh Magazine, May - June 2012