Cut the turkey fillet into equal cubes. Peel the sweet potato and cut it into pieces of approximately two centimeters. Finely mince the half onion. Rinse the green beans, trim the ends and halve them. Have the broth ready for immediate use.
Place a braising pan on the stove and brown the turkey cubes on all sides over medium-high heat. Add the minced onion to the meat. Cook this together for a few minutes until the onion looks translucent and begins to soften.
Add the sweet potato pieces to the pan and pour in the broth. Bring the liquid to a boil, then turn the heat down to low and cover the pan. Let the dish simmer gently for twenty minutes. Stir in the green beans during the last five minutes of cooking time so they become tender-crisp.
Check that the turkey is fully cooked and the potato has the right tenderness. Remove the pan from the heat, divide the warm stew onto plates and serve the meal immediately.