To make the seasoning, mix all the ground ingredients together and store in an airtight jar.
In a bowl, mix 1 tbsp olive oil with the grated garlic, lemon juice and shawarma seasoning to make the marinade. Make 2-3 diagonal slits on each chicken breast and coat well with the marinade. Cover and rest for at least 2 hours to overnight.
To make the tahini sauce, whisk all the ingredients together in a bowl, thin with water to the desired consistency. It should not be very runny.
Heat the remaining oil in a pan on medium heat. Once the pan is hot, put in the chicken breasts, slit side down. Allow the chicken to char and cook for 3-4 minutes before flipping to cook the other side for 3-4 minutes more.
Let the cooked chicken rest for 10 mins on a board or plate before slicing each breast into 5-6 thick slices.
Toss all the other salad ingredients with some of the dressing. Divide the salad between 2 plates, Place 1 chicken breast on top of the salad on each plate, drizzle with dressing and serve.