Rinse the grains and place them in a medium pot along with 2 teaspoon salt and enough water to generously cover. Bring to a boil. Reduce the heat to medium-low and maintain a gentle but steady simmer until the grains are tender to the bite. The exact amount of time will depend on the grain used, from 15 minutes for quinoa to 60 minutes for wheat berries. Drain the grains and set aside.
If using greens with thick stalks, such as Swiss chard or kale, cut the stalks from the leaves. Finely chop the stalks, then cut the leaves into thin ribbons, keeping the stalks and leaves separate. If using greens without thick stalks, simply chop the leaves into ribbons or bite-size pieces.
Heat 1 tablespoon olive oil in a soup pot over medium-high heat. Add the stalks, if using, and cook, stirring frequently, until they’re soft, about 5 minutes. Add the garlic and stir to combine. Add the chicken stock or vegetable broth plus the drained, cooked grains and bring almost to a boil. Add the greens (stalks and leaves), stir to combine, and cook until the greens are wilted and tender, just 1 or 2 minutes for spinach, 5 minutes for chard or bok choy, and up to 10 minutes for hearty kale.
Season with salt and a grind or two of pepper and, if desired, a drizzle of oil. Ladle it up while warm. Leftovers will keep, covered, in the refrigerator for 2 or 3 days and in the freezer for up to 3 months.