Heat oil in a medium stockpot over medium heat. Add chicken and brown, stirring occasionally, about 5 minutes. Remove chicken from the pot and set aside.
Add onion to the pot and cook, stirring frequently, until soft and lightly browned, about 3 minutes. Add garlic and spinach and cook, stirring, until spinach is wilted, 1 to 2 minutes. Stir in the Kitchen Accomplice Chicken Broth Concentrate or Chicken Bone Broth Concentrate, water and tomatoes. Bring to a boil, add rice, then reduce heat to low and simmer for 15 minutes, or until rice is just tender.
Return chicken to the pot and simmer for another 5 minutes, until it is cooked through. Season the chicken and rice soup to taste with salt and pepper.