Every time I cook from a recipe that calls for just part of a vegetable, I feel like crap—I don't have a compost bin, which means all those scallion greens or tomato skins wind up going straight into the trash. What else can you really do with 'em?
What if I told you that there's actually a great use for these cast-off ingredients, and that it's simple, fast, fun, and delicious? A way that will land you with brightly hued powdered seasoning that's great for rimming cocktail glasses and sprinkling on everything from fried chicken to fresh mozzarella?
Of course, the idea of transforming vegetable scraps into something that tastes good and lasts in your pantry is nothing new. Chefs do it all the time, and we've even written up DIY tomato powder in the past. What's special is using the microwave to do in mere minutes what it takes the traditional low-oven method hours to accomplish.
I took some cues from a post we ran a while back about drying herbs in the microwave to preserve flavor and even color. The same principles apply here: simply lay the ingredients on a paper towel, cover them with another paper towel, and microwave them on high until they're dry to the touch. The process is incredibly simple, and all you'll need are vegetable scraps, the microwave, and a spice grinder or mortar and pestle.
If you're wondering why on earth you'd ever have a pile of tomato skins in the first place, take a quick gander at the step-by-step process and one of our favorite uses for skinless tomatoes: refreshing, smooth-textured coulis. Once your tomato skins are in-hand, pat them dry with a towel and lay them out in a single layer on a stack of two or three paper towels, cover them with another paper towel, and stick them in the microwave on a heat-resistant dish. Be sure not to press the top towel down—I had some skins stick to the towel when I tried pressing out extra moisture that way.
After about four to five minutes in the microwave, they should be papery and crisp, with almost the same bright red hue you started with. A quick spin in the spice blender turns them to a fine or coarse powder.
I've found that the best flavor comes from ripe, flavorful tomatoes—no surprises there. This is a powder I'd only bother with in summer months; bland supermarket tomatoes will yield a flavorless seasoning that you'll wish you'd never bothered with. To amp up the tangy-sweet tomato flavor, I add a pinch of both salt and sugar to the skins once they're in the spice grinder; I'd avoid mixing in strong spices or aromatics, which would likely overpower the delicate flavor.
The process for scallion powder is virtually the same, except that scallion greens have a higher moisture content than tomato skins. I was able to reduce the microwave time by several minutes by thinly slicing the greens before microwaving. Working with just half a bunch at a time also helps evenly dehydrate each batch.
The scallion powder is sweet, grassy, and just a little peppery. I don't add salt or sugar, but either would complement the greens well, as would garlic powder or onion powder. Just mix in any additional seasonings in small increments to avoid overwhelming the scallions altogether.
And that's about all you need to know to start making your own vibrant vegetable powders, no dehydrator necessary. Just be sure to store them in air-tight containers to preserve as much flavor as possible—they'll last around a month and don't need to be refrigerated. Both powders have relatively delicate flavors, so I wouldn't recommend cooking with them. Instead, toss 'em on potato chips or popcorn, sprinkle some on your caprese salad, or use them to coat the rim of your next Bloody Mary—the world is your tomato and scallion-dusted oyster.