Heat the olive oil over medium heat in a large stock pot or Dutch oven.
Sprinkle a bit of salt and pepper over the chicken tenders. Once the oil is hot, place the chicken tenders into the pot and cook for about 4-5 minutes on each side, until they're slightly golden in color and have an internal temperature of 160º F.
Transfer the chicken to a paper towel lined plate.
Drizzle a bit more oil to the pot if necessary; add the onions and a sprinkle of salt. Let the onions simmer until they sweat, about 2-3 minutes; stir in the garlic, Italian seasoning, and sun-dried tomatoes.
Add the flour, mixing it in until the veggies are coated.
Add the wine and let it simmer for 2-3 minutes. Pour in the broth, bring the heat up to medium-high and let the soup come to a rolling boil.
Once boiling, bring the heat back down to low. Add the spinach and simmer for about 15 minutes. In the meantime you can shred your chicken tenders with two forks, then add the chicken to the soup as well.