Turn on a multi-functional pressure cooker (such as Instant Pot) and select the Sauté function. Add oil and warm for a few minutes. Add onion and celery; sauté for 2 minutes. Add carrots; sauté for 4 minutes. Add garlic and cook for 2 minutes. Stir in ham, lentils, basil, oregano, and thyme. Pour in chicken broth, tomato sauce, and water, then stir in bay leaf.

Close and lock the lid. Select high pressure according to the manufacturer’s instructions; set the timer for 8 minutes. Allow 10 to 15 minutes for pressure to build.

Release pressure using the natural-release method according to the manufacturer’s instructions, 10 to 40 minutes. Carefully remove the lid and discard bay leaf. Stir in salt, lemon juice, and pepper.