1 Mix The Green Onion, Parsley, Tarragon, Lemon Juice, Lemon Zest, Dijon Mustard, Black Pepper, And Mayonnaise In A Medium Sized Bowl. Add The Drained Tuna, Mixing With A Fork To Break Up The Flakes. 2 Lay Out Four Slices Of Bread. Divide The Tuna Mixture Evenly Onto The Slices. Top Each Bread Slice With Tomato Slices And Grated Cheese. Spread One Side Of The Remaining Four Bread Slices With Butter. Place Bread Slices, Buttered Side Up, On Top Of The Cheese. 3 Heat A Large Griddle, On Medium Heat (Or Couple Cast Iron Skillets). Place The Sandwiches, Buttered Side Down, Onto The Hot Griddle. Gently Spread Butter On Top Of The Bread Slices. Cook For About 3 Minutes, Or Until Nicely Browned On One Side. Then Use A Metal Spatula To Lift Up The Sandwiches And Carefully Turn Them To The Other Side. Cook For Another 3 Minutes Or So, Until The Second Side Is Browned.