Slate-Grilled Porterhouse, Summer Vegetables, and Sourdough Bread

INGREDIENTS

• 4 olive oil plus more for slate
• 2 2–2 1/2-inch-thick porterhouse steaks (about 4 pounds total), room temperature
• 1/4 herbes de Provence
• Kosher salt, freshly ground pepper
• 3 small Italian eggplants (about 1 1/2 pounds), halved lengthwise
• 6 small beefsteak tomatoes (about 2 pounds), halved crosswise
• 3 small zucchini (about 1 pound), halved lengthwise
• 3 portobello mushrooms (about 1 pound), stems removed
• 2 large red bell peppers (about 1 pound), Cut lengthwise into 1 1/2-inch strips
• 6 garlic cloves, thinly sliced
• 1/3 fresh rosemary leaves
• 1/2 olive oil
• 1 medium round loaf sourdough bread (about 1 1/2 pounds), cut into 1-inch wedges
• 1/4 olive oil
• 1 garlic clove, halved
• Kosher salt
• A few 16x16-inch untreated natural slate floor tiles 1/4–1/3 inch thick (in case one breaks)