Top-ranked recipe named "Filet Oscar Style"
Steam the crab legs: Preheat oven to 375. Place the king crab legs in a loose-fitting foil pouch. Before sealing tightly, add a small amount of water. Place in the oven for 10-12 minutes. Using a fork or a crab-leg-meat-getter-outer, remove the meat from the crab legs and place in a medium bowl along with the blanched asparagus tips. Gently break up any overly-large pieces with your hands.
Cook the steaks: In a large, oven-safe saute pan, melt butter and olive oil over medium-high heat until very hot. Pat the steaks dry and season both sides liberally with sea salt and cracked black pepper. Place the steaks in the pan and sear 3-4 minutes. Flip, sear for 3 minutes more and place the pan into the oven. Cook to an internal temperature of 135 (medium rare), remove from oven and tent with foil while you finish the sauce.
Make the B?arnaise sauce: Boil wine, vinegar, shallots, and fresh tarragon in a small heavy saucepan until liquid is reduced to 2 tablespoons, then strain through a fine-mesh sieve set into a medium bowl, pressing on and then discarding solids.
Whisk the yolks into the vinegar mixture, and then set bowl over a double boiler and cook until hot, whisking constantly until yolks have thickened slightly. Whisk in butter 1 piece at a time, adding each piece before previous one has melted completely. Remove from heat and whisk in lemon juice, 1/2 teaspoon salt, and 1/2 teaspoon pepper (or to taste). Keep warm, if necessary, by leaving it on the double-boiler but make sure to turn off the heat.
Assemble: Add about 1/3 cup of the sauce to the bowl of crab and asparagus. Lightly toss to coat. Plate the steaks and top with a generous portion of the crab-asparagus mixture. Top with additional B?arnaise sauce and serve.