Add all ingredients to the slow cooker except bay leaves and cornstarch. Stir until well combined and add bay leaves on top.
Cover and cook on high for 2⅓-3½ hours or low for 4-6 hours.
Remove the bay leaves and ½ cup of broth. Mix the broth with cornstarch and pour it into the gumbo. Stir until well combined. Continue to cook for 15 minutes or until the sauce thickens.
Serve over rice and garnish with fresh parsley.
Notes
The "Holy Trinity”: Onion, bell pepper, and celery give this gumbo authentic Gulf Coast flavor.
Andouille and Cajun seasoning can be salty, so taste before adding extra salt.
Adjust the heat to your preference. Use more cayenne or add hot sauce if you like it spicy, or go mild with less spice.
Leftovers stay fresh in the fridge for a couple of days, or freeze up to three months for easy future meals.