Preheat a grill to 275-300F for indirect cooking. Add a dutch oven hanging over the fire to preheat for 5 minutes (control the heat of the dutch oven by raising or lowering to the heat).
Add the beef tallow to the dutch oven and let melt (about 5 minutes). Next, add your rosemary, thyme and garlic cloves to the tallow to infuse for 5 minutes. When the tallow is between 120-160F, add the plain steaks to it making sure they are fully submerged and cook until they are 115F internal (about 10-15 minutes). Once the steaks are done & have hit temperature, pull them off and let them rest for 10 minutes.
While the steaks rest, build a high heat fire (around 400F) for searing on your grill.
Pat the steaks dry from any excess tallow and season on all sides with salt, pepper and garlic powder. Add the steaks to the grill to sear for 1-1.5 minutes per side until they are crispy. Pull the steaks off once done and keep warm
Next, add a skillet to the grill at medium heat (about 300F) to heat up. Add some beef broth and heavy cream and let simmer for 2-3 minutes. Next, add your blue cheese crumbled and hatch chiles. Simmer over the flames, stirring often, until it has thickened and reduced (about 10-15 minutes). Once done, pull off and keep warm.
Slice your steak and top with the Hatch Chile Blue Cheese Sauce. Garnish with chopped chives, serve and enjoy!