Turn the instant pot on sauté mode and add pancetta. Sauté for 5 minutes until fat is rendered.
Add anchovies, onion, carrots, celery, mushrooms and garlic and sauté for 5 to 6 minutes until veggies are tender.
Add grass-fed beef, salt and pepper and stir to combine with veggies. Sauté for about 5 minutes until the meat is just cooked through.
In a bowl, pour the whole peeled tomatoes and break apart into smaller chunks using your hands. Add the tomatoes, tomato sauce and tomato paste into the instant pot and stir. Bring to a boil and add coconut aminos and stir.
Once sauce is boiling, turn the instant pot to a simmer by using either the slow cook function or a low sauté function depending on your instant pot.
Simmer at low for at least 4-8 hours. The longer you can simmer, the better the flavors will combine.
15 minutes before serving, put the instant pot back on sauté mode and add coconut milk. Stir until combined and the sauce is boiling. Reduce heat back to a simmer for 15-30 minutes.
Serve over spaghetti squash or your favorite grain free pasta!