1.Place A Steamer Insert Into A Saucepan, And Fill With Water To Just Below The Bottom Of The Steamer. Cover, And Bring The Water To A Boil Over High Heat. Add The Broccoli And Steam Until Just Tender, 2 To 6 Minutes Depending On The Size Of The Broccoli Florets. Remove The Broccoli To A Serving Bowl And Toss With Butter, Add Salt And Pepper To Taste. 2.Heat The Tuna, Teriyaki Sauce, And Garlic Powder In A Skillet Over Medium Heat. Cook And Stir Until The Tuna Has Heated Through, About 5 Minutes. Pour The Tuna Over The Broccoli And Serve.