Add all ingredients except bell peppers to the instant pot. Lock lid. Set valve to sealing. Program for manual, high, and 22 minutes. Quick release. Open lid. Add bell peppers. Stir well. Lock lid. Set valve to sealing. Program for manual, high, and 0 minutes. Quick release. Serve over cooked brown rice, if desired.
Note: if cooking in the instant pot from frozen, be sure to freeze in a shape that fits into the instant pot. You can do this by placing your bag in your insert and then freezing overnight, or you can use 64 oz freezer containers. (See notes).
There is no need to alter the time if cooking from frozen in the instant pot. The cook time will remain the same, though it will take the pot longer to reach pressure if the contents are frozen.