Amount	Ingredient
1 Teaspoon	Dijon mustard
1 (5.33-Ounce)	FROZEN TURKEY BURGER, grill flavored
1	Kaiser roll, split and toasted
2 Thin slices	red ripe tomatoes
1 to 2 leaves	romaine lettuce, washed, drained and chilled
1 Tablespoon	sour cream
1-Ounce slice	Swiss cheese
1-Ounce	thinly sliced fresh mushrooms, lightly sautéed
1 Tablespoon	thinly sliced fresh scallions