1 Peel The Onions, Then Cut In Half From Root To Top. Slice The Halves Into Thick Wedges, Making Sure To Keep Some Of The Root End Attached; This Will Help Keep The Onion Wedges From Completely Falling Apart On The Grill. 2 Coat The Onions In The 2 Tablespoons Olive Oil And Some Salt. Prepare Your Grill For High, Direct Heat. Grill The Onion Wedges On Each Side Until You Get Nice Grill Marks, About 3-5 Minutes Per Side, Depending On How Hot Your Grill Is. After You'Ve Achieved Grill Marks On The Second Side Of Each Onion Wedge, Turn The Grill Down To Medium-Low (Or Move Some Of The Coals Away From The Grill Grate), Cover And Roast For 15-20 Minutes To Soften The Centers Of The Onions. 4 While The Onions Are Cooking, Make The Dressing. Put The Mustard, Minced Shallot, Garlic, Salt, Rosemary, And Vinegar In The Bowl Of A Blender, And Pur