Place chicken breast in a shallow dish and cover with sangria. Cover and marinate, refrigerated, for 2 hours, up to overnight.

Remove chicken from marinade and grill on a non-stick skillet (or traditional grill) over medium heat, roughly 10 minutes per side, until cooked through. (Cooking time will vary depending on the thickness of your chicken breast.)

While the chicken is cooking, place the sangria marinade into a small saucepan and bring to a simmer. Continue to heat until wine has reduced by half (20 min).

In a small, non-stick frying pan, heat oil. Add celery and onion and sauté over medium heat until golden (10 min). Remove onion mixture from the heat and mix in cornstarch, so that no lumps remain.

Add veggies to reduced sangria and simmer 3-5 minutes to continue to thicken.

To serve, cover chicken with sangria sauce. Serve with rice and green vegetables.