Cook pineapple juice in small saucepan over medium heat until reduced to 1/2 cup. Remove from heat and add tequila. Let cool.

Place tuna steaks in a medium-sized shallow baking dish and pour in pineapple glaze sauce. Coat tuna steaks completely- both sides. Cover and refrigerate for 1 hour.

Heat grill pan over high heat. Add salt and pepper to tuna steaks. Grill steaks on each side for 2-3 minutes.