Cauliflower Steaks with Olive Relish and Tomato Sauce

INGREDIENTS

• 2 tablespoons chopped flat-leaf parsley
• Kosher salt and freshly ground black pepper
• 1/2 cup pitted oil-packed black olives, finely chopped
• 2 plum tomatoes, cored, quartered
• 3 sun-dried tomatoes, thinly sliced
• 1 large head of cauliflower
• 3 garlic cloves
• 3 1/2 tablespoons olive oil, divided, plus more
• 1 teaspoon fresh lemon juice