Sprinkle your fish fillets with salt, pepper and dried oregano.
Place butter into your Instant Pot and press “Sauté”.
Add onion, garlic, tomatoes, chili powder and a pinch of salt.
Cook for about 4 minutes, until you obtain a sort of thick sauce.
Add your fish fillets and cook for another 2 minutes.
Add 2 tbsp water, lock your Instant Pot and cook for about 5 minutes at high pressure.
Release the steam quickly and serve your fillets topped with their spicy tomato sauce and sprinkled with fresh cilantro.