Season both sides of chicken thighs with Ultimate Steak Seasoning. Set aside.
In large skillet, heat Avocado Oil over medium-high heat. Add chicken; sear until browned on both sides, about 3-4 minutes. Remove from skillet; set aside.
Add mushrooms and Onion Onion Seasoning to skillet; add ¼ cup chicken broth to pan to deglaze, if needed. Sauté until lightly browned, about 3-4 minutes.
Stir in chicken broth and Spinach & Herb Seasoning. Add chicken back into skillet. Cover and simmer until internal temperature of chicken reaches 165°F on an instant-read thermometer, about 8-10 minutes.
Meanwhile, in small bowl, whisk together arrowroot powder and water. Stir into skillet; simmer 2 minutes. Remove from heat; stir in tomatoes.