For Veal Steak: Combine steak ingredients such as finely chopped mushrooms, eggs, 1/3 cup tabasco chipotle pepper sauce, 1/4 cup minced onion, parsley, 3/4 tsp. salt and 3/4 tsp. black pepper in large bowl; mix lightly but thoroughly. Divide and shape into twelve 1-inch thick patties, about 8 oz each. Cover and refrigerate.
For Avocado Salsa: Combine avocados, tomatoes and white onion in medium bowl. Season with salt and pepper to taste. Cover and refrigerate.
For Mashed Potatoes: Cook potatoes in boiling salted water until fork-tender; drain. Place potatoes in mixer bowl. Mix on low speed, adding milk, 3/4 cup butter, cheese and 1 tbsp. chipotle pepper sauce, until smooth. Season with salt and pepper to taste. Keep warm.
For Mushroom Sauce: In large skillet sauté shallots and garlic in 3 tbsp. oil until tender. Add remaining 3 tbsp. oil and quartered mushrooms; sauté until tender, stirring often. Add wine; reduce to au sec. Add veal stock; about 15 minutes or until thickened and syrupy. Combine 1/4 cup butter and flour until smooth; whisk into sauce. Simmer about 5 minutes or until thickened, stirring occasionally. Season with 1-1/2 tsp. salt and pepper. Keep warm.
Brown burger on both sides in hot skillet. Finish cooking in 350°F oven to medium (160°F) doneness.
Place burger in center of plate. Top with 1 cup mashed potatoes and 1/3 cup salsa. Finish with 4 oz sauce.