Dice the onion, potatoes, and squash. Slice the carrots and mince the garlic.
Combine the vegetables, lentils, broth, herbs, and salt in a crock pot. Cook on low for 8 hours.
When finished cooking, put the oil and about 4 cups of the soup in a blender. Blend until pretty smooth - the oil should combine evenly with the other ingredients, giving it a creaminess. Add back into the rest of the soup, along with 2 Tbsp vinegar. Stir together and serve!
Soup gets better the next day! The acid from the vinegar balances the heartiness of the soup, but can get overhwelming if you add too much. Add to taste.