It’s hard to cook asparagus to its elegant best. If you leave spears in too long, they go from vibrant and crisp to drab and droopy. Take them out too soon, and you’ll get a raw crunch instead of a tender, tasty bite. But it’s easy to cook asparagus perfectly in this soup. There’s no peeling or fussy prep. No matter how long the asparagus simmers, it doesn’t lose its sweet, earthy flavor. A touch of thyme and savory add garden brightness, and golden potatoes make it creamy. Crispy, salty prosciutto bits on top give contrasting crunch and color to the green smoothness. Best of all, you don’t need pristine spears if you’re just…