Gather all of your ingredients then preheat the oven to 450 degrees F and place a large cast iron skillet in the oven for about 5 minutes until it's smoking hot. Turn on a stovetop burner to medium-high heat.
Pat the meat dry with paper towels and season both sides of the steak generously with salt and pepper.
Using an oven mitt, carefully remove the hot cast iron skillet from the oven and place it on the hot stovetop burner. Add the canola oil to the skillet, carefully swirl it around to coat the pan, and then add the deer steak.
Let steak sizzle for about 2 minutes, then use tongs to flip it over and cook about 2 more minutes. Press down gently to ensure even contact between steak and pan. When the steak has developed a dark brown crust on both sides, add 1 tablespoon of butter to the skillet and immediately transfer the skillet to the oven.
After 3 minutes, use aninstant-read thermometer to insert into side of steak to check the internal temperature. For medium-rare meat, 125 to 130 degrees is ideal. Keep checking the steak every 90 seconds until you reach the proper temperature.
While the steak is in the oven, start to make the sauce. Melt together the cream cheese and salsa verde in a small saucepan over low heat, whisking constantly until the cream cheese has melted and the mixture is nice and creamy. Remove from the heat until ready to use.
Once you've reached a perfect medium-rare temperature, remove the steak and transfer it to a cutting board and tent lightly with foil. Let rest 5 to 10 minutes. The steak will continue cooking after being removed from heat.
Turn down the oven temperature to 250 degrees F and place the flour tortillas in the oven for 5 minutes. Remove the tortillas and place them in a tortilla warmer or wrap them in aluminum foil until ready to use.
While the deer steak rests, use the same skillet to sauté the onions with another 1 tablespoon of butter until the onions are softened, about 4 minutes. Add the bell peppers and cook another 2 minutes. Now add the minced garlic and sauté another 2 minutes. Remove the skillet from the heat.
Now thinly slice the deer steak with a sharp knife, cutting away from your body and with the top edge of the knife leaning toward your body. Make sure to slice across the grain of the meat. Now add the steak to the onions and peppers along with the cumin, oregano, smoked paprika, and chili powder and toss to combine.
Stuff the deer steak, onions, and peppers into the warmed tortillas, and top with the creamy salsa verde sauce, cilantro, and queso fresco. Add a couple slices of jalapeno for those who like it extra spicy!