How to Make It
Preheat the oven to 425°. Season the tenderloins all over with salt and pepper. In each of 2 large deep skillets, melt 1 tablespoon of butter in 1 tablespoon of olive oil. Add the tenderloins to the skillets and cook over high heat until browned all over, about 8 minutes. Transfer to a rack and let cool slightly.
In a small bowl, combine the ketchup, mustard and egg yolks and brush the mixture all over the tenderloins. Transfer the meat to a large roasting pan. Sprinkle the pecans all over and press to help them adhere. Roast in the middle of the oven for about 25 minutes, until an instant-read thermometer inserted in the thickest part of each tenderloin registers 125° for medium-rare. Cover the roasts loosely with foil if the coating browns too quickly. Transfer to a cutting board and let stand for 10 minutes.
Meanwhile, pour off the fat in one of the skillets used for browning the meat. Add 1 tablespoon of the butter. Add the shallots, garlic and carrot and cook over moderate heat, stirring occasionally, until softened and just beginning to brown, about 6 minutes. Add the tomato paste and juniper berries and cook, stirring, for 2 minutes. Add the wine and cook over moderate heat, scraping up any browned bits stuck to the bottom of the skillet, until the sauce is slightly thickened and reduced to 1/2 cup, about 10 minutes. Add the demiglace and bring to a boil. Strain the sauce through a fine sieve into a small saucepan, pressing hard on the solids. Season the jus with salt and pepper and stir in the remaining 1 tablespoon of butter.
Carve the roasts and serve with the juniper jus on the side.
Beef demiglace is available in the freezer section of large supermarkets and specialty-food shops.