Thaw the turkey. If we buy a frozen one we leave in the fridge, not the freezer, for a few days. Pre heat the oven to 375°F. Remove the neck and giblets. Rinse it inside and out. Put it in a pan big enough to hold it. Yeah, I really just said that. Cut the lemon into 4 pieces and mash the garlic cloves without removing the skin then put the lemon and garlic inside the bird. Generously sprinkle the turkey with salt and black pepper. Spread the chopped carrots, celery and onions (aka Mirepoix) in the pan all around the turkey. Add the 2 cups of water. Cover it with aluminum foil folding the foil around the edges of the roasting pan. Put it in the oven. At 375°F a 12 to 14 lb. turkey is going to take 3 1/2-4 hours. After 2 1/2 hours remove the foil and continue the roasting. When a meat thermometer inserted into the thickest part of the thigh but not touching the bone reads 165°F it’s done! Take it out of the oven and move the turkey to another pan or a casserole dish to let it settle down before carving it.