Combine the cubed chicken, spices, and 2 teaspoons of neutral oil in a bowl. Toss to coat until the chicken is coated. Cover and refrigerate for 30 minutes to 24 hours.
Brown the chicken:
Heat 1 tablespoon neutral oil in a large pot over medium-high heat. Add half the chicken and arrange it into an even layer. Cook for 4–5 minutes, stirring occasionally, until it browns and crisps around the edges. It does not need to be cooked through. Transfer to a bowl. Add the rest of the chicken and cook for 4–5 minutes. Transfer to the bowl.
Make the chili:
Add 1 tablespoon of neutral oil to the pot over medium heat. Add the diced onion and cook for 3 minutes. Add the jalapeño, minced garlic, chili powder, cumin, and cayenne powder. Cook for 1 minute. Season lightly with salt.
Add the kidney beans, green chilies, sweet potatoes, tomatoes, and chicken broth. Add the chicken and bring to a boil. Reduce the heat and simmer, uncovered, for 1 hour. Taste and adjust the seasonings to your preference. Mash a few of the sweet potatoes as they soften to help thicken the chili. Remove from heat.
Prepare the garnishes:
As the chili finishes simmering, prepare whatever garnishes you like and arrange them on a platter.
To serve:
Serve the chili at the table alongside the platter of garnishes. Spoon the chili into bowls, allowing guests to garnish as they like. Enjoy!