I start most soups with bacon cut into lardoons, and add garlic when the fat is rendered out. Then onions or leeks, celery, carrots and whatever other veg are involved, dried herbs (especially bay leaves and thyme), sauté a bit more, then lentils or barley or rice, then stock. Cook for a while, taste. Add salt (if necessary) and black pepper. Taste again.

At this point, if the soup is still blah, it's time for Worcestershire sauce, or perhaps a shot of lemon juice. Lentil soup benefits from a hunk of orange rind in the bouquet garni, and a large pinch of rosemary.