Begin by thinly chopping your shallots. Add them to a paper towel and squeeze out all the excess water. Set to the side to dry out. Finally, lather your steaks with oil and generously season with salt, pepper and garlic or your favorite steak rub. Set in the fridge until ready to cook.
Preheat a fire for medium high heat (about 375F). Add a dutch oven or a deep skillet to the fire to preheat.
Add enough oil to the skillet to be 1” high and heat up till 375F. Carefully add your sliced shallots to the oil to fry for only 3-4 minutes until golden brown. Do this in batches so as not to overcrowd the skillet. Finally, pull the fried onions out and pat dry. Season with salt, pepper and garlic. Keep warm until serving.
Next, add your filets to the grill and cook for 3-4 minutes per side or until they are 120F. Once the steaks are done, pull off and let rest for 10 minutes.
Add a cast iron skillet back to the fire and cook your minced garlic for 2 minutes or until browned. Add your coarse black pepper and stir around. Deglaze with the cognac then add your beef stock and dijon mustard. Let the sauce simmer over the flames until thickened (about 7-10 minutes). When the sauce has thickened, add your creme fraiche and stir. Pull off and keep warm.
Slice your filets and cut your entire slider roll in half. Begin building your sliders in a foil bin with the base of the slider rolls, swiss cheese, sliced steak, more swiss cheese, fried shallots and the top of the slider rolls. Spread out some butter over the top buns and place back in the grill to cook indirectly at 300F for 10 minutes. Once the sliders are golden brown and the cheese has melted, pull off and slice them up. Serve with the sauce on the side. Enjoy!