Broiled Portobello Mushrooms with Sauteed Vegetables

Name: Broiled Portobello Mushrooms with Sauteed Vegetables
Ingredients: 0.25 cup balsamic vinegar; 0.25 cup olive oil; 5 sprigs fresh thyme, leaves stripped; 1 medium lemon, juiced; 2 large portobello mushroom caps; salt and ground black pepper to taste; 2 tablespoons olive oil; 1 zucchini, chopped; 1 red bell pepper, chopped; 1 medium beefsteak tomato, diced; 2 artichoke hearts, drained and chopped; 2 cloves garlic, minced; 10 leaves fresh basil, chopped; 0.25 cup panko bread crumbs; 0.5 cup grated Parmesan cheese, divided