Heat the avocado oil in a large thick-bottomed pot such as a Dutch oven over medium-high heat. Allow the oil to heat up for a few minutes, until it becomes sizzling hot. Carefully place the boneless skinless chicken thighs in the pot in a single layer and sear for 3-4 minutes per side, until golden-brown. Use tongs to move the chicken to a plate and set aside (note: it does not need to be cooked through just yet).

Place the pot back on the stove top and add the chopped onions. Sauté the onion over medium heat, stirring occasionally, until softened, about 8 minutes.

Transfer the browned chicken back into the pot with the minced garlic, kalamata olives, sun-dried tomatoes, capers, artichoke hearts, brown rice, broth, and Italian seasoning (everything expect for the spinach). Give everything a big stir, cover the pot, and bring it to a full boil. Reduce the heat to a very gentle boil and cook for 45 minutes (note: if you have more time, feel free to cook longer). Use tongs to move the cooked chicken thighs to a cutting board and use two forks to shred them. Transfer the shredded chicken back into the soup pot along with the chopped baby spinach. Continue cooking until the spinach has wilted, about 3 minutes.

Taste the soup for flavor and season it to your personal taste with sea salt and black pepper.

Serve soup in big bowls alongside any side dishes you enjoy, such as crusty garlic bread, cornbread and butter, a side salad, etc.