April 22 is officially Earth Day. Of course, the whole point of Earth Day is to remind us to reduce our impact on the Earth all year long. Each of us has the power to make positive change, by reducing the amount of resources we consume and waste we generate. If that sounds overwhelming, let me suggest a focus for your efforts.

Keep it simple. Eat more plants, and stop wasting so much food. One effective tool for doing both is to make your own stock, so read on for a recipe for vegetable stock and a tasty Italian Mushroom and Farro Soup.

One-third of all the food produced globally is wasted, somewhere along the way. It's easy to buy food with the best of intentions, and end up with a garbage can full of wasted food at the end of the week. Tons of perfectly good food gives up the ghost and becomes waste every day.

If you really want to cut back on waste, you have to plan your shopping lists. When you buy fruits and vegetables, have a menu set for the week that uses them up. If you will only eat three apples this week, just buy three and not more. Resolve to go through the refrigerator a couple of times a week, looking for food that needs to be used up.

A classic strategy is to wring all the value you can from your vegetables by making the trims into stock. As a soup maker, I've always saved onion, celery, carrot, herb stems and other flavorful bits to go into stock. You don't need strict measurements to make stock, but you do need to follow a couple of important guidelines.

First, stick to the more neutral veggies, unless you want a stock with a strong flavor. Peppers, broccoli, cauliflower and cabbage can overpower the stock. If you have a shriveled sweet potato, wrinkled squash or zucchini, or a few soft tomatoes, throw them in. A soft apple can add a little sweetness.

Secondly, don't boil the stock. It may seem like it would save time, but it only makes it bitter. Unlike meat bones, you can coax the flavor out of vegetables with a gentle simmer, in under an hour.

Once you have vegetable stock, you can make soup, cook pilafs with it or make sauces. It freezes well, too.

Make every day Earth Day, by making the most of your plants.

Robin Asbell is a cooking instructor and author of "Big Vegan" and "Plant-Based Meats." Find her at robinasbell.com.