How can I cook moist turkey tenderloin?

Inject it with a brine that is 2 parts water to 1 part salt (you will need the tool for that but it's cheap) Inject a small amount of brine into the meatiest part. It will keep the interior moist as opposed to dried out and boring.

Slice it and stuff with a bit of bread crumb, sage, finely chopped apples, and celrey. Season with salt on the inside.
Wrap with bacon slices and tie it up. Sear it off to start the crisp. Finish in a oven at about 325 for 20 mins. (or until temp reaches 140...let it rest..and slice and serve with a gravy, mashed potatoes, a veggie and green salad.

Slice it and stuff with a bit of bread crumb, sage, finely chopped apples, and celrey. Season with salt on the inside.
Wrap with bacon slices and tie it up. Sear it off to start the crisp. Finish in a oven at about 325 for 20 mins. (or until temp reaches 140...let it rest..and slice and serve with a gravy, mashed potatoes, a veggie and green salad.

From our recipe book
TURKEY BREAST STUFFED WITH GRAPES AND HERBS

1 turkey breast
4 cloves garlic
3 rosemary branches
8 sage leaves
1 cup white wine
3 cups of milk or broth
8 grapes
olive oil
salt pepper

There are two herbs chopping.
Inside -Garlic, sage and little rosemary, salt and pepper.
Sauce -Garlic and rosemary.

Peel the grapes and cut in halves, take the seeds out and keep enough halves of grapes to pave a good part of the turkey.
Open the turkey breast and pound to have a flat surface. Cover the inside with the previously chopped herbs, add the grapes and roll closed. Tie the roll closed with kitchen string.

Heat the oil in a pan and place the turkey roll in the pan. Brown on all sides for 10 minutes.
Remove the oil used for browning, clean the pan with a paper or cloth. Add new olive oil.
When again at temperature add white wine. When the wine has evaporated, add the broth to cover half of the turkey and cook on a low flame for 25 minutes depending on the size of the turkey, add more broth if evaporates. Use hot broth not cold.
Add the milk to cover half of the turkey and let evaporate. Here check if the milk not sticking to the pan. Add the sauce herbs salt and pepper (but taste before as you don't want too much salt) when milk almost all evaporated, and cook another 5 minutes.

Cut in slices and serve the sauce on the slices

(www.cooking-class-authentic-tuscany.com)

Consider papillote, or poaching.

http://food52.com/recipes/20964-stuffed-turkey-breast-marsala-or-poor-man-s-veal, shredded turkey in black bean chili with cornbread (its cold here today), pho, or saag turkey?