Rinse rice in a sieve with cold water until water runs clear. This is highly recommend it to prevent rice from clumping and sticking together.
In a large skillet over medium heat add olive oil and onion. Cook for a couple of minutes and add garlic.
Season chicken with salt, pepper, and cumin. Add chicken to pan and sear until browned on both sides. Don't worry if chicken is not cooked through, it will continue to cook with rice. Remove chicken from pan and set aside.
Add rice to pan and cook with onion and garlic until slightly toasted. Add in tomato sauce and vegetables. Pour in chicken broth and slightly stir mixture. Add salt as needed.
Place chicken thighs back in pan on top of rice. Cover with lid and let it cook for about 30 minutes over medium heat. If liquid remains after 30 minutes, cook for additional 5 minutes until all liquid is absorbed. Turn off heat and leave covered for additional 10 minutes.