Step 1

Use the saute button on the Instant Pot, then add the oil and butter, when melted add the celery, carrots and onions; cook 5 to 6 minutes, or until tender.

Step 2

Add the flour, stir and cook 1 to 2 minutes. Add the broth, milk, and pour the juice of the tomatoes into the Instant Pot, then roughly crush the tomatoes with your hands; add to the pot. Add the thyme, basil, and bay leaves and parmesan rind if using.

Step 3

Cover and cook high pressure 30 minutes. Quick or natural release, remove the cheese rind and herbs then blend the soup using an immersion blender until smooth (or you can carefully do this in small batches in the blender).

Step 4

Add the 1/3 cup grated Pecorino cheese, salt and pepper, adjusting to taste.

Step 5

To serve, ladle into bowls, top each with basil and 1 teaspoon parmesan.