Beef Tips in Mushroom Sauce Crock Pot Recipe. 2 pounds lean chuck – cut in 1 – 3/4 inch pieces, 1 can 98% fat free cream of mushroom soup, 1 pkg. onion soup mix, 1 can Diet Sprite or 7Up. Put meat in crock pot. Pour soup & onion soup mix over meat. Add Diet Sprite/7up. Cook in crock pot all day on low (or high for at least 4 hours). Turn off and let sit for 30 minutes before serving.