Let the checca sauce and chicken marinade for at least four hours, or ideally overnight, so the poultry soaks up the flavors.
In a resealable plastic bag combine the checca and chicken. Seal the bag and toss to coat. Place in the refrigerator and allow to marinate for at least 4 hours or up to overnight.2.
Preheat a grill or grill pan to medium heat. Allow the chicken to come to room temperature for 10 minutes.3.
Remove the chicken from the marinade and dry well on paper towels. Season all sides evenly with the salt and drizzle with the olive oil. Place the chicken on the hot grill pan, smooth side down. Cover and allow to cook, undisturbed for 5 minutes. Flip the chicken and cook, covered, for an additional 4 to 5 minutes or until an internal temperature on an instant read thermometer reads 160 degrees. Remove the chicken to a plate and spoon 1 tablespoon of sauce on each breast. Allow to rest for 5 minutes.4.
Meanwhile, for the checca, bring the water and salt to a boil in a small sauce pan. Turn off the heat and stir in the couscous. Cover and let sit for 5 minutes. Stir in the checca.5.
In a medium bowl toss together the arugula, fennel, lemon juice, olive oil and salt. Divide the couscous among 4 plates. Top with a sliced chicken breast and some of the salad nestled on the side. Serve with additional checca if desired.