Heat oil in nonstick skillet on medium-high heat. Add squash and mushrooms, cooking until slightly soft; remove from skillet. Add chicken to skillet and cook 6-8 minutes. Return squash and mushrooms to pan; add black beans, grenadine, orange juice, chili powder, tequila, garlic powder, and chicken stock.
Lower heat to medium and cook for 5 minutes. In separate bowl, combine cornstarch and water until smooth; add to skillet mixture and stir until thickened. Add tomato and heat through. Portion mixture evenly among tortillas and fold classic style. Serve immediately.