Turn Instant Pot on saute mode. Heat 1 tbsp olive, then add green pepper and onion. Saute until softened, about 4 minutes. Add garlic and saute for about 30 seconds. Turn off Instant Pot.
Remove mixture from Instant Pot and set aside. Clean bottom of pot and then spray clean pot with cooking spray.
Add fire roasted tomatoes, chiles, chicken broth, chipotle salsa, brown sugar, cocoa powder, chili powder, cumin, salt, cloves, cinnamon and coriander to pot. Stir until well combined. Stir in sauteed vegetables. Place chicken in mixture.
Cook on high pressure for 10 minutes and let natural release for 10 minutes.
Remove chicken from mixture and shred with two forks. Use immersion blender to carefully blend sauce (if you do this, let it cool for 5-10 minutes first), or transfer to blender. After sauce is blended, while continuously stirring, gradually sprinkle in corn starch. Let sauce simmer for 5 minutes.
Stir chicken in sauce. Serve over rice or in tacos.