Awhile ago a Vidalia onion farm hired me to develop recipes for their baby Vidalia onions that are sold with the greens still attached. They only wanted recipes that used the bulbs but I couldn't toss those tops without doing some experimentation first. I tried various ways of cooking them and used them in a bunch of recipes. What I learned: (1) Once they're simmered for a few minutes, you get a nicely flavored vegetable broth that you would swear resulted from hours of simmering several kinds of veggies. (2) You can freeze the tops and then pull them out and simmer them from frozen when you want an instant veggie broth. (3) The tops become softened and more edible once they're simmered. My favorite way to eat them: I remembered a heartbreakingly good Onion Walnut Bread recipe by Jane Grigson and decided that walnuts would have to be involved somewhere. I developed this robust pesto recipe and it is now my favorite way to eat the tops. I am so happy that I didn't throw them away! To serve: Toss 2-3 tablespoons of pesto plus 1-2 tablespoons of pasta cooking water with each serving of hot cooked pasta. Top with grated parmesan cheese. —Cook the Story
In a medium saucepan bring 4 cups of water to the boil. Add the onion tops and reduce heat to low. Simmer for 1-2 minutes, just until wilted (they should still be bright green). Drain the onions (reserve the liquid for another use – it is a flavorful vegetable broth).
Spoon the onion tops into a food processor or blender. Add the parsley, walnuts, ¼ teaspoon of coarse salt and ¼ cup of olive oil. Purée. While the blade is still running, gradually add another ¼ cup of olive oil. Taste. Add more salt if necessary (I usually add about another ¼ teaspoon).