Thai basil changes a pot of soup the moment it hits the heat. One handful can turn broth from pleasant to fragrant, savory, and bright, with a flavor that lands somewhere between anise, mint, clove, and pepper.

Quinoa can turn a simple pot of soup into a meal, but it can also go mushy, bitter, or bland if it is treated like an afterthought. The good news is that quinoa is easy to cook well once you know two things: rinse it, then season it with the same care you give the broth.

Eggplant can make a soup taste richer, silkier, and more satisfying, but only if it is prepared well. Undercooked eggplant can feel spongy. Overcooked eggplant can disappear into the pot. Season it too lightly, and it tastes flat. Season it with a little care, and it becomes one of the best vegetables for building deep, cozy flavor.