Prepare the red bean and rice dinner according to package directions. While it cooks, cut the venison into bite-sized pieces and sprinkle with Cajun seasoning. Toss the venison in the seasoned flour mixture. Reserve 1 tablespoon of the seasoned flour mixture after dredging the venison.
Brown the floured venison pieces in hot oil.
Heat ¼ inch of vegetable oil in a heavy pot or Dutch oven over medium-high heat. Brown the venison in batches, being careful not to overcrowd the pan. Once all of the venison has been browned and removed to a warm platter, add the reserved tablespoon of seasoned flour to the pan.
Add flour to the oil and stir to form a roux.
Stir the flour into the remaining oil until it takes on a dark blonde color, about 5 minutes. Pour in the beef broth and stir and scrape the bottom of the pan to loosen any stuck-on bits. Bring the pot to a boil and reduce the heat to low. Simmer until the stock begins to thicken to the point that it will coat the back of your spoon, about 3 minutes.
Return the venison to the pot. Add the cooked red bean and rice mixture to the pot, then pour in the red enchilada sauce. Bring to a simmer and stir until the mixture thickens, usually 5 to 8 more minutes.
Simmer the red beans and rice and fried venison in the sauce.
Spoon the mixture down the center of a warmed flour tortilla and top with cheese and sour cream if desired.