In a medium saucepan, heat 2 tablespoons of butter until melted. Then add shallots and cook for about 3 to 4 minutes, or until soft. Pour in the white wine and deglaze the pan. Next, add the thyme and vanilla. Bring to a boil and continue boiling for 4 to 5 minutes or until the liquid is reduced by half of its volume. Add the cream and bring back up to a boil. Once at a boil, reduce the heat to medium-low and simmer for 4 to 6 minutes, or until the mixture thickens. Remove from the heat, season with salt and cool. Blend the cream mixture in a blender and strain through a fine mesh strainer, and then set aside. In a saute pan, over medium heat, melt 2 tablespoons of butter. Add the cooked potatoes and cipollini onions and cook for 2 to 3 minutes, or until warm. Add the cream mixture and cook for another 3 to 4 minutes so that the potatoes and onions get coated with cream. Set aside until ready to serve.
To make the Piquillo Crab Sauce:
In a medium saucepan, heat the olive oil over medium-high heat. Add the shallots and cook until softened, about 2 to 3 minutes. Pour the white wine and lemon juice into the pan and stir to combine. Lower the heat to medium and add the smoked paprika and heavy whipping cream. Cook for 1 minute and then add the piquillo peppers, cooking for 1 minute more. Remove the pan from the heat, letting it cool briefly, and then pour mixture into a blender. Blend the red pepper mixture on low, then increasing to high, until smooth. Season the mixture with salt and then pour into a clean saucepan over medium heat and add the butter, gently stirring to combine. Add the crabmeat and cook for 1 to 2 minutes, or until the crabmeat is heated through. Reduce heat to low and simmer sauce until ready to serve.
To make the beef tenderloin:
Preheat an oven to 350 degrees F.
Place the beef tenderloin steaks on a clean work surface. Pat dry and then season with salt and freshly ground black pepper. In a large, oven-proof saute pan or skillet, add 2 tablespoons vegetable oil and heat over medium-high heat. When the oil shimmers, add the tenderloins and sear on 1 side, about 2 to 3 minutes. Flip steaks to cook on the second side and then immediately place the skillet in the oven to finish cooking, about 4 minutes more.
To serve, spoon a portion of the Vanilla Potatoes on the center of a plate. Place a tenderloin steak on top of the potatoes and then spoon a portion of the Piquillo Crab Sauce on top of the steak.