Sauté Sausage: Set your Instant Pot to the sauté function. Add olive oil, and when it's hot, add the Italian sausage. Break it up with a spoon and cook until browned, about 5 minutes. Remove any excess fat if necessary.

Sauté Aromatics: Add the diced onion, carrots, and celery to the Instant Pot. Sauté for about 3-4 minutes until the vegetables begin to soften.

Add Tomato Paste: Stir in the tomato paste and cook for an additional 2 minutes to enhance its flavor and reduce any raw taste.

Add Garlic and Spices: Add the minced garlic, bay leaf, dried rosemary, and dried thyme. Sauté for another 1-2 minutes until the garlic becomes fragrant.

Combine Lentils and Diced Tomatoes: Stir in the lentils and diced tomatoes (with their juice). Mix everything together.

Add Chicken Broth: Pour in the chicken broth, ensuring it covers all the ingredients. Stir well, scraping the bottom of the pot to release any browned bits.

Pressure Cook: Cancel the sauté function, secure the Instant Pot lid, and set it to pressure cook on high for 8-10 minutes. Ensure the steam release valve is sealed.

Natural Release: Once the cooking cycle is complete, allow for a natural pressure release for about 10-15 minutes. Carefully open the steam release valve afterward to release any remaining pressure.

Season and Serve: Open the Instant Pot lid, and remove the bay leaf. Season the soup with salt and black pepper to taste. Stir well.

Enjoy: Ladle the soup into bowls, and serve it hot. Optionally, garnish with fresh herbs or grated Parmesan cheese for extra flavor.