Place the tamarind, orange juice, lime juice, garlic, ginger and salt in a baking dish and stir to combine. Add the chicken thighs to the marinade, cover and refrigerate for at least 8 hours or overnight.

About 30 minutes before time to cook, remove the chicken from the marinade and pat dry. Lay the chicken onto a rimmed baking sheet and allow to come to room temperature. Meanwhile, heat the oven to 450 degrees.

Place the chicken in the oven and cook for about 35 to 37 minutes (or until the thighs are cooked through to 165 degrees).

While the chicken is roasting, pour the marinade into a small saucepan and bring to a fast boil on high heat. Maintain high heat until the marinade is reduced to a thick sauce. Stir occasionally to prevent sticking and remove from heat once the desired texture is achieved.

Once the chicken is finished roasting, brush the marinade on top of each chicken thigh and top with chopped cilantro. Serve warm.