Whisk all the marinade ingredients (2nd - 7th) in a bowl. Cut the meat off the bone of the Sadia Chicken Thighs, keeping the skin on. Cut into large bite-sized pieces and combine with the marinade. Cover and refrigerate for at least 20 minutes or up to 24 hours.
Cut the watermelon into small 1 cm thick triangles and set aside.
Whisk all the dressing ingredients (13th- 15th) in a small bowl and season to taste.
Heat a large frying pan over medium-high heat. Cook the chicken until golden brown and fully cooked. Drain on kitchen towels.
Put the chicken, watermelon, spinach, red onion and olives in a large bowl. Add the dressing and gently toss. Transfer the salad to a serving platter and scatter the feta all over.