Heat vegetable oil in a large stockpot or Dutch oven over medium heat. Add onion and peppers, and cook, stirring occasionally, until tender, about 3-4 minutes.
Stir in garlic, chili powder, cumin and oregano until fragrant, about 1 minute.
Stir in chicken stock, diced tomatoes, and chicken; season with salt and pepper, to taste. Bring to a boil; reduce heat and simmer until flavors have blended, about 20 minutes.
Remove chicken from the Dutch oven; shred, using two forks.
Stir in chicken, heavy cream and lime juice until heated through, about 2 minutes. Stir in cilantro; season with salt and pepper, to taste.
Serve immediately with crispy tortilla strips and desired toppings.
For the crispy tortilla strips
Heat vegetable oil in a large cast iron skillet or Dutch oven over medium high heat. Working in batches, add tortilla strips to the Dutch oven and fry until evenly golden brown and crispy, about 1-2 minutes. Transfer to a paper towel-lined plate.