Preheat oven to 325°.
Combine the soft butter with the salt, pepper, mustard and chopped herbs until throughly combined.
Heat the oil in a heavy-bottomed sauté pan until it shimmers, then add the bacon.
When the bacon is cooked, add the leek and sauté in the oil/bacon on medium-high heat.
Lightly sauté the leek for a minute until it becomes fragrant and then add the fennel. Cook the bacon/fennel/leek mixture until the vegetables are soft.
Add the chopped garlic and sauté until you smell the garlic and as soon as you smell the garlic add the white wine.
Spread the herb butter evenly onto the fish and top with breadcrumbs.
Place the buttered filet on top of the sautéed vegetable/bacon mixture and place in the oven.
Allow the fish to cook on the bed of vegetables until its internal temperature reaches 120°. This will take approximately 15 minutes.
Serve fish with the sautéed vegetables and your choice of sides (this dish is excellent served simply with with rice, farro or quinoa). Garnish with Extra-virgin Olive Oil, fines herbs and lemon juice.