Steamer baskets make quick work of meal preparation. While you assemble the ingredients in the baskets (try our suggestions, or improvise), bring one inch of water to a simmer in a large skillet or a wok. Place the stacked baskets in the water, and cook for about 10 minutes. If the sweet potatoes aren't done, remove the top two baskets, cover potatoes, and continue cooking. These five-inch baskets hold a single portion; double the ingredients and use larger baskets to serve two.
Fill the top basket with quick-cooking greens, since they will get the lightest steam. We used 1 cup packed baby spinach and topped it with thin slices of red chile for a little heat.
Fish and Flavorings
Combine fish and aromatics in the middle basket: Split 1 leek in half lengthwise (pale-green part only). Cut 2 outer leaves of leek in half crosswise, and layer in basket to form a base; reserve remaining leek for another use. Season 1 black cod fillet (about 4 ounces) with salt and pepper, and place on leek leaves. Sprinkle 1 teaspoon orange juice and 1/4 teaspoon finely grated orange zest on top of fish.
Place slow-cooking vegetables in the bottom basket, which gets the biggest blast of steam. Peel 1 sweet potato (about 8 ounces), and cut into 1 1/2-inch-thick slices. Arrange in basket, and scatter four 1/4-inch-thick slices fresh ginger over sweet potatoes.