Place dried porcini in a small bowl and cover with 1/2 cup hot water. Soak 20 minutes until softened. Reserve the soaking liquid by straining through a fine sieve or coffee filter; reserve both mushrooms and liquid separately.

Process crust

Roughly chop rehydrated porcini (squeeze out excess liquid) and pulse in a food processor with panko, grated Parmesan, minced garlic, and chopped thyme until evenly combined but still slightly textured. Add 2 tablespoons softened butter and pulse until mixture holds together when pressed. Season with 1 teaspoon kosher salt and 1/2 teaspoon black pepper. Transfer to a shallow dish.

Season filets

Bring filets to room temperature (30 minutes). Pat dry with paper towels. Season all over with remaining kosher salt and pepper. Brush the top of each filet with about 1/2 tablespoon Dijon mustard to help the crust adhere.

Sear and finish in oven

Preheat oven to 400°F (200°C). Heat an ovenproof skillet over medium-high heat and add 2 tablespoons olive oil. Sear the filets, mustard-side down first, for 1-2 minutes until deeply browned, then flip and sear the other side 1 minute—do not cook through. Remove skillet from heat. Press a generous 2-3 tablespoons of the porcini-panko crust onto the top of each filet, pressing gently to adhere. Place skillet in the oven and roast 6-9 minutes for medium-rare (internal temp 125-130°F / 52-54°C). Transfer filets to a cutting board and tent loosely with foil for 5-7 minutes to rest.

Ulu Pomme Purée

Place ulu and Yukon Gold potato in a medium pot and cover with cold salted water. Bring to a boil and simmer until tender, about 15-20 minutes. Drain well and return to pot. Warm the heavy cream and butter together until butter melts (microwave or small saucepan). Mash the ulu and potato with a potato masher or ricer until smooth. Gradually stir in warm cream-butter mixture until silky and smooth. Season with 1 teaspoon salt and white or black pepper to taste. Keep warm, cover, and hold until plating.

Madeira Bordelaise

In a small saucepan over medium heat, melt 2 tablespoons butter. Add minced shallot and cook 2-3 minutes until softened but not browned. Add Madeira and red wine vinegar; simmer and reduce by half (about 4-6 minutes). Add beef demi-glace, thyme sprig, and reserved porcini soaking liquid (if desired, strain and add up to 2 tablespoons for extra umami) and simmer until sauce coats the back of a spoon, about 6-8 minutes. Remove thyme sprig. Whisk in remaining 1 tablespoon cold butter off the heat to gloss the sauce. Season with 1/2 teaspoon salt and 1/4 teaspoon pepper. Keep warm.

Mushrooms and Tomatoes

While filets roast, heat 1 tablespoon olive oil and 1 tablespoon butter in a sauté pan over medium-high heat. Add sliced shallot and garlic and cook 30 seconds until fragrant. Add Hamakua mushrooms and sauté, stirring, until they begin to brown, about 4-5 minutes. Add cherry tomatoes and continue cooking until tomatoes blister and soften but remain mostly whole, about 2-3 minutes. Season with 1/2 teaspoon salt and 1/4 teaspoon pepper. Remove from heat and keep warm.

Finishing and Plating

Divide warm ulu pomme purée between four plates, making a shallow well in the center. Place a rested porcini-crusted filet on top of each purée portion. Spoon warm Madeira bordelaise sauce over and around the filets (about 2 tablespoons sauce per filet). Arrange a spoonful of sautéed Hamakua mushrooms and blistered tomatoes alongside each filet. Sprinkle microgreens or chopped parsley over the dish and finish with a light pinch of flaky sea salt. Serve immediately.