Tex-Mex Chicken and Squash Stew

Mix cilantro, cumin, oregano, salt and pepper in a medium bowl. Add chicken; toss to coat, pressing mixture to adhere if necessary. Coat a large nonstick skillet with nonstick spray. Heat over medium heat, add chicken and onions, and cook, turning chicken once, 4 to 5 minutes until browned. Add remaining ingredients except frozen squash, if using. Bring to a boil, reduce heat, cover and simmer about 25 minutes, adding frozen squash for last 10 minutes, until chicken is cooked through and squash is tender.