Preheat oven to 425°. Toss together potatoes, oil, and 1 teaspoons salt in a bowl. Spread potatoes in a single layer in a jelly-roll pan, and bake 35 to 40 minutes or until golden and tender.
Meanwhile, stir together turkey, egg, dijon, breadcrumbs, pepper, and seasoning salt in a large bowl. Shape into 6 (3 1/2-inch) patties.
Cook patties in a large skillet over medium-high heat 4 to 5 minutes on each side or until browned. Remove patties, reserving drippings. Sauté onion in hot drippings 2 minutes. Add tomatoes, bouillon, and 1/2 cup water. Cook, stirring occasionally, 3 to 4 minutes or until bubbly.
Return patties to skillet; spoon tomato mixture over patties. Cover and cook 15 minutes; uncover and cook 5 minutes. Place 1 cheese slice on each patty. Cover and cook 3 minutes. Sprinkle with basil, if desired. Serve with potatoes.