How to Make It
Whisk together 1 cup hot water and demi-glace in a small bowl until dissolved; set aside. Cook bacon in a high-sided large skillet over medium, turning occasionally, until crisp, 10 to 12 minutes. Transfer bacon to a plate lined with paper towels, reserving drippings in skillet.
Add quartered mushrooms, onion, and 2 tablespoons butter to bacon drippings in skillet. Increase heat to medium-high, and cook, stirring often, until mushrooms are lightly browned, about 10 minutes. Stir in wine, and bring to a simmer; cook 5 minutes. Stir in demi-glace mixture, ketchup, maple syrup, onion powder, garlic powder, chili powder, and Creole seasoning. Return to a simmer over medium-high. Reduce heat to medium; and gently simmer, stirring occasionally, until sauce is thick enough to coat the back of a spoon, 5 to 7 minutes. Remove from heat, and stir in 1/2 teaspoon salt. Cover sauce, and keep warm.
Heat oil in a large nonstick skillet over medium-high. Sprinkle fillets with remaining 1 1/2 teaspoons salt. Place fillets in hot pan; cook until edges are golden brown, about 5 minutes. Carefully turn fillets over; add remaining 1/4 cup butter. Tilt skillet so butter pools, and cook, basting fish often, until just cooked through, about 3 minutes. Remove from heat.
Place 1 fillet in each of 4 shallow bowls. Spoon about 1/2 cup sauce over and around each fillet. Top evenly with crumbled bacon and remaining thinly sliced mushrooms. Garnish with herbs.
Look for veal demi-glace in quality butcher shops or online.