Cut up rotisserie chicken (or cut up whole chicken breasts), and season with lemon pepper, or saute raw chicken in olive oil, (about 2 tbsp), with lemon pepper and salt. Meanwhile, start the water for the orzo. Cook the orzo per package directions. Remove chicken from pan, add more olive oil if necessary, (1 or 2 tbsp), and add the spinach. Saute a couple of minutes until it starts to wilt, then add the tomatoes and continue cooking. Add more salt if necessary. When tomatoes and spinach have cooked down, turn the heat way down and add the cooked orzo,crumbled feta cheese, and champagne or sherry vinegar. Stir to combine everything, then add the chicken to the pot and cover and heat until the chicken is warm.