Add shallots and garlic and cook until soft. About 5 minutes.
Immediately turn back down to medium-low and let simmer, uncovered, until reduced by half, about 15 minutes.
Turn the heat back down again to medium-low and simmer again for about 5 more minutes.
Pour the marinade over the meat and put it in the fridge. Let it sit for 2 hours or overnight.
Pre-heat a cast iron skillet over medium high heat for about 5 minutes.
Immediately turn it down and simmer on medium-low for about 10 minutes. It should be thick and have a jam like consistency.
Throw your steaks into the skillet and sear for 2-3 minutes on each side for medium-rare.