1. Dry the chicken fillet in paper towel and marinate them with mustard, olive oil, garlic and thyme, season with salt & pepper. Refrigerate overnight or until the marination absorbs by the chicken.
2. Boil the potato in salted water, once the potato are soft strain them, let the steam runs out. Use a potato masher or grater.
3. In a saucepan heat the milk with butter, add the mashed potato and season with salt and pepper. Mix thoroughly.
4. Steam the vegetables in a steamer for 5 to 10 min. In a nonstick pan over high heat grill the chicken fillet 2 min. on both sides or until the chicken is done.
5. Serve the potato and vegetables with the grilled chicken fillet.