New York City-Style Porterhouse Steak - The Grill Dads

Ingredients

• 1 2-inch thick porterhouse steak, at least 2 pounds total
• Kosher salt (for seasoning)
• 1 medium red onion (peeled and halved)
• 2 tablespoons olive oil
• 4 ounces 1 stick high-quality butter, at room temperature
• 1 teaspoon lemon juice
• 1 tablespoon finely chopped parsley
• ½ teaspoon kosher salt