Heat a large cast-iron skillet over medium high heat then add 1 tablespoon butter and 1 tablespoon oil. Saute sweet potatoes, stirring occasionally until browned and almost tender. Transfer to a bowl and set aside.
Pat steak dry and season both sides with salt and pepper. Add remaining butter and oil to pan over medium-high heat then add steak once pan is hot. Sear steak 2-3 minutes on both sides until golden-brown then transfer to a plate (steak will not be fully done yet)
Drain grease from pan and add garlic to remaining pan drippings, sauteeing 1-2 minutes until fragrant. Add orange juice, honey, mustard, and rosemary and bring to a low simmer over medium-high heat, stirring occasionally until sauce is reduced and thickened.
Toss sweet potatoes back into pan and into the sauce. Nestle steak into the sweet potatoes and spoon some of the sauce over top. Place skillet in oven and roast at 375F 8-10 minutes until sweet potatoes are tender and steak reaches your desired temp (NOTE: if you prefer your steak more on the rare side, do not cook a second time in oven and keep warm elsewhere OR remove the steak from the oven a bit earlier and keep cooking the sweet potatoes until they are tender)
Let steak rest 10 minutes then slice against the grain and serve with the sweet potatoes, orange sauce, and additional orange wedges if desired. Enjoy!