Preheat grill to medium-high or oven to 450 degrees.
Open foil bag. Lightly spray inside of foil bag with nonstick cooking spray. Combine water and flour; pour inside foil bag. Combine rosemary, thyme and tarragon. Rub over turkey breast. Sprinkle with seasoned salt and pepper. Place turkey breast in foil bag.
To seal, double fold open end of foil bag. Place foil bag in a 1-inch deep pan. To cook, slide foil bag onto grill or leave foil bag in supporting pan and place in oven.
Grill 1 to 1 1/2 hours in covered grill OR bake 1 1/2 to 1 3/4 hours in supporting pan in oven. Meat thermometer reads 170 dgrees when done.
Use oven mitts to cut open foil bag with sharp knife. Carefully fold back top of foil bag, allowing steam to escape. Let stand 15 minutes before slicing. Makes 10 to 12 servings.