Select the saute function on the Instant Pot. Once the pot is hot, coat the bottom with oil. Toss in onion, garlic, and bell pepper. Saute for 3-4 minutes, or until veggies are softened and onion is translucent. Select cancel.
In a small bowl, stir together paprika, cumin, chipotle spice powder, and sea salt. Dump in the Instant Pot and stir. Now pour in the the fire roasted tomatoes with juices. Continue to stir ingredients, making sure to scrape the bottom of the pot so none of the veggies are sticking. Place the chicken on top, then pour broth over the mixture.
Now secure the lid. Select the manual function and cook on high pressure for 15 minutes. Use a natural release for 10 minutes, then release any remaining steam. Once the pressure is completely released, remove the lid.
Squeeze in lime juice and stir in any additional salt to taste. Shred the chicken with a fork, or use a knife to cut if needed.
Serve hot with fresh cilantro, jalapeno and avocado, if using.
For the slow cooker, dump all ingredients (not the lime, cilantro, jalapeno, or avocado). Cook on low for 6 hours. Shred chicken with a fork and serve hot with toppings.