Use a cutting board and large sharp knife to dice the bell pepper (removing stem and seeds first) into roughly half inch pieces. Place the diced bell pepper in a small bowl with the onion that's already diced and take out the kohlrabi.
First prep the kohlrabi by removing the leaves and stems. Next slice the hard skin off the top and bottom. Then either peel the rest of the skin away with a vegetable peeler, or if it's too hard you can cut it away with a knife. Cut the white, inner part of the kohlrabi into half inch pieces. Set the kohlrabi aside while you get the soup going.
Take out your large pot and set in on the burner of a stove over medium heat. Measure out the oil with a measuring spoon and pour it in the pot. When the oil is hot (after a minute or two), pour in the diced onion and bell pepper. Measure out 1/2 teaspoon of the kosher salt and pour it in the pot. Cook for 5 minutes, stirring with a wooden spoon or other utensil every so often to keep the veggies from burning.
While the bell pepper and onion are cooking, open up the cans of crushed tomatoes and chiles and set aside. Once the veggies are softened, press the garlic and put it in the pot, along with the measured out ground cumin, smoked paprika, and another 1/2 teaspoon kosher salt. Stir together and cook for 30 to 60 seconds, just until fragrant.
Pour the crushed tomatoes, chiles, kohlrabi, stock, and the rest of the salt into the pot and stir to combine. Cover the pot with a lid, increase the heat to high, then bring the pot to a boil. Once it boils, reduce the heat to low and cook for 20 to 30 minutes, until the kohlrabi if fork tender. Add in the chopped turkey and stir, then cook for another 5 to 10 minutes until the turkey is heated through. Taste to see if you'd like to add in more salt. Top with sliced avocado and chopped cilantro, if desired. If not on a Whole30, crumble paleo tortilla chips on top for some crunch.