Grilled Veggie Panini

Why I Love This Recipe
Let the grilling begin ... with summer just around the corner :). Only instead of ribs or a juicy hamburger, its grilled veggie panini today.
Serve this with a nice tall cool drink and your favorite chips. Enjoy!
NOTE:
I used a heavy cast iron skillet to press the sandwich down on the grill.
This gives the sandwich ridges and the bread will grill to a perfect crisp on the outside.
Ingredients You'll Need
Oil for brushing
Portobello mushrooms
Yellow squash, sliced lengthwise
Zucchini, sliced lengthwise
Tomatoes, sliced
Red onions, sliced
Red wine vinegar
Sourdough bread
Slices provolone cheese
Basil
Directions
Heat grill.
Brush vegetables with oil.
Grill mushrooms, squash and zucchini for 2–3 minutes on each side or until well-defined grill marks appear.
Place the onions and tomato slices on top of aluminum foil and place it on the grill to prevent them from falling through the grids.
In a large mixing bowl, toss all of the grilled vegetables with red wine vinaigrette and allow to marinate for at least 30 minutes.
Dress your sandwich in whichever way you like and divide the vegetables evenly.
Grill the prepared sandwich for a few minutes on each side until bread is slightly toasted.