If your lamb has been cooking in the crockpot for 6 hours and you find it's not as tender as you'd like, there are a few things you can do to help improve its tenderness:
Cook it longer: Lamb can become more tender the longer it cooks. If you have the time, you can continue cooking the lamb in the crockpot on a low setting for an additional 1-2 hours or until it reaches your desired level of tenderness.
Check the temperature: Use a meat thermometer to check the internal temperature of the lamb. Lamb becomes more tender as the collagen in the meat breaks down into gelatin. The internal temperature should be around 190°F (88°C) for the collagen to break down fully and the meat to become tender.
Add liquid: If the lamb appears to be dry or tough, you can add some liquid to the crockpot to help keep it moist. You can use broth, wine, tomato sauce, or a combination of liquids to add flavor and moisture to the meat.
Use an acidic marinade: Before cooking the lamb in the crockpot, you can marinate it in an acidic mixture, such as lemon juice, vinegar, or yogurt. The acid helps break down the muscle fibers and can contribute to the meat's tenderness.
Consider using a different cooking method: If the crockpot method isn't achieving the level of tenderness you desire, you can try other cooking methods like braising or roasting. Braising involves cooking the lamb in a covered dish with liquid in the oven at a low temperature, while roasting requires higher heat in an uncovered dish.
Slice and simmer: If you've already cooked the lamb for a significant amount of time and it's still not as tender as you'd like, consider slicing the meat into smaller pieces and simmering them in a sauce on the stovetop. The smaller pieces will cook more quickly and have a better chance of becoming tender.
Remember that the tenderness of lamb can vary depending on the cut and quality of the meat. Some cuts are naturally more tender than others, so keep that in mind when selecting your lamb for cooking. Additionally, be patient when cooking tougher cuts of lamb, as it may take longer to achieve the desired tenderness.