Prepare grill by having two heat zones: 1) high heat and 2) medium heat with a medium cast iron pan placed on the grate.
Pat prawns dry with a paper towel. In a mixing bowl, toss prawns with canola oil, 1-teaspoon salt and 1/2-teaspoon pepper.
Season strip steaks with remaining salt and pepper. Grill over high heat 4-5 minutes per side or until they reach an internal temperature of 125°F for medium rare. Allow to rest, tented with foil, while preparing prawns.
Grill prawns over high heat, 2 minutes on one side. While prawns grill, add 4-tablespoons butter and garlic to the cast iron pan (over medium heat). Flip prawns and grill 2 more minutes. Transfer to cast iron pan and stir in parsley and lemon zest; searing 2 more minutes.
Remove from heat, stir in remaining 2-tablespoons butter and lemon juice until melted. Serve steaks topped with prawns and drizzled with scampi butter.
