Combine jalapeno, orange zest and juice, garlic, soy, fish sauce, and brown sugar in a large zipper bag. Add chicken thighs, squeeze out air and seal bag. Refrigerate, turning occasionally, at least 3 hours or up to overnight.
Spray grill rack with non-stick cooking spray. Preheat grill to medium high.
Remove chicken from marinade and discard marinade. Grill chicken until instant-read thermometer registers 165 degrees, about six minutes per side. Remove from heat, cover with foil, and allow to rest for 5 minutes before serving.
Serve with Mango Salsa.
Per Serving (1 chicken thigh and 1/4 cup relish) = 6 WW Pts+ If served with 1/2 cup cooked couscous & mixed greens with balsamic vinegar, add 3 WW Pts+