Put Ground Beef, Mustard, Garlic, Onions, Blue Cheese, Water, Egg, And A Sprinkling Of Salt And Pepper Into A Large Bowl. Use Your Hands To Gently Mix The Ingredients Together Until Just Incorporated. Do Not Over-Mix. Shape Into Patties, About 1/2 Inch Thick And Larger Than Your Bun. Chill Until You Are Ready To Cook. Prepare Charcoal Or Gas Grill For Cooking Over High Direct Heat. Using Tongs And A Folded Up Paper Towel Dipped In Vegetable Oil, Oil The Grill Grates. Make Sure Grill Is Hot And Well Oiled Before Laying Down The Patties. Season Patties With Salt And Pepper. Place The Patties On The Clean, Well-Oiled Grill Grate. Grill The Burgers For About 5 Minutes Per Side. Do Not Press Down On The Burgers While Cooking. If You Don'T Have A Grill, You Can Use A Grill Pan Or A Cast Iron Frying Pan For The Burgers. Serve On Hamburger Buns With Lettuce And Mayonnaise.