Saute the chopped onion, diced jalapeno, and minced garlic in a small skillet with 1 tsp olive oil over medium heat until fragrant, about 2 minutes.
Place the sauteed veggies along with the rest of the ingredients (except for the corn tortillas) inside the slow cooker, and cook on high for 4 hrs or on low for 8.
Make the crispy tortilla strips: heat one tablespoon of olive oil in a medium-sized skillet over medium heat and pan-fry the tortilla strips until crunchy.
Remove the chicken breasts from the crockpot 10 minutes before the cooking time is over, shred them, and return them to the pot.
Serve with diced avocado, fresh cilantro, sour cream, and crunchy tortilla strips as garnish.