Watercress Soup
Watercress grew wild in the chalk streams of southern England and made its way into one of the country's oldest soups, a bright green bowl that tastes of pepper and spring. It also happens to be built on the single most nutrient-dense food per calorie ever measured, which is reason enough to cook it. The base is the classic British move of leeks and potato: the leeks sweated slow to stay sweet and pale, the potato simmered soft to give the soup its creamy body with no cream at all. The cress goes in only at the end, wilted for a minute so it holds its color and its bite, then everything is blended smooth. Soy milk finishes it rich and a squeeze of lemon sharpens it in place of salt. It is as good cold in July as hot in March.
Ingredients
- 8 oz Watercress
- 2 wholes Leeks, white parts sliced
- 3/4 lb Potatoes, peeled and diced
- 2 cloves Garlic, sliced
- 1 tbsp no-salt vegetable bouillon
- 1/2 cup Unsweetened soy milk
- 1/4 tsp Nutmeg, freshly grated
- 1/2 tsp Black peppercorns, freshly ground
- 1 tbsp Lemon juice
Method
- Sweat the leeks and garlic in 0.25 cup (60 ml) water in a covered pot over medium heat until soft and sweet, about 8 minutes, adding a splash more water if the pot runs dry. Leeks are milder and sweeter than onion, and cooking them gently under a lid steams them tender without browning, keeping the soup pale so the green of the cress reads clean later.
- Add the diced potatoes, the bouillon, and 3 cups (710 ml) water. Simmer until the potatoes are completely soft, about 12 minutes. The potato is the body of the soup: blended, it makes it thick and velvety with no cream, and cutting it small means it cooks fast and purees smooth.
- Stir in the watercress and cook just 1 to 2 minutes, only until it wilts. Watercress is added at the very end on purpose; a long simmer turns it drab olive and cooks out its peppery bite, while a brief wilt keeps both the color and the mustard-like kick that make the soup.
- Blend the soup until completely smooth, then return it to low heat and stir in the soy milk, nutmeg, and black pepper. Blending while the cress is still bright locks in the green, and the soy milk adds a creamy finish and a little protein, the richness a British kitchen would once have gotten from cream.
- Take it off the heat and stir in the lemon juice. The acid lifts the whole bowl and sharpens the pepperiness of the cress, standing in for the salt the soup carries none of. Taste and add a little water if it is thicker than you like.
Nutrition
Estimated per serving: 150 calories, 6 g protein, 4 g fiber, 110 mg sodium. Computed from USDA FoodData Central reference values for the main ingredients. This is an approximation, not a laboratory measurement. How these are computed.
Cost per serving is estimated from US national-average retail prices for cheap staple forms, using BLS dried-bean prices and USDA produce prices. Prices vary by store and season, so treat it as a guide, not a receipt. How this is computed.
