Directions

1. Place the mushrooms, eggplant, winter squash, and zucchini into a shallow bowl or baking dish. Drizzle with the balsamic vinaigrette, turning to coat evenly. Cover, and refrigerate at least 2 hours, or up to 24 hours, stirring occasionally.
2. Preheat grill to medium-high heat.
3. Drain vegetables and discard marinade. Place vegetables on preheated grill, and cook until lightly browned, turning once, or about 3 minutes on each side. (Note that cooking times vary between grills.) Sprinkle the mushrooms with blue cheese, and let the cheese melt slightly.
4. Open the 6 hamburger buns and divide the eggplant, squash, and zucchini among bottom halves. Place the portobello mushrooms on top of the vegetables, cheese side up. Top with the remaining 6 hamburger bun halves. If necessary, use toothpicks to hold the buns in place. Serve immediately.