Sopa de Agrião, Portuguese Watercress Soup
Sopa de agrião is a quiet Portuguese classic, the watercress cousin of the better-known caldo verde. It is built the same frugal way: a base of potato and onion simmered soft and part-blended for body, then a great heap of greens stirred through at the end. Watercress is the most nutrient-dense green there is by weight, and it brings a peppery bite that a squeeze of lemon sharpens further, so the soup needs no salt to taste finished. Keeping the cress in the pot for only a couple of minutes is what preserves both its color and its punch. It costs very little, comes together in one pot, and reheats well, though the greens are brightest the day it is made.
Ingredients
- 6 cups Watercress, roughly chopped, thick stems removed
- 3/4 lb Potatoes, peeled and cubed
- 1 Yellow onion, diced
- 2 cloves Garlic, sliced
- 1 tbsp no-salt vegetable bouillon
- 1 tbsp Lemon juice, fresh
- 1/4 tsp Black peppercorns, freshly ground
Method
- Sweat the onion and garlic in a pot with a splash of water over medium heat until soft and translucent, about 6 minutes. Cooking them gently in water first, without letting them brown, keeps the base sweet and clean, which is how a Portuguese vegetable soup starts.
- Add the potato, the bouillon, and 4 cups (1 L) water. Simmer until the potato is completely tender, about 20 minutes. The potato is the body of the soup, so cook it soft enough to blend without a trace of grain.
- Blend about half the pot until smooth, then stir it back in, or mash the potato against the side with a spoon. Pureeing part of it gives a creamy base with no cream while leaving some texture, the usual Portuguese way with a caldo.
- Bring it back to a simmer and stir in the chopped watercress. Cook just 2 to 3 minutes, only until it wilts. Watercress loses its pepper and its color if it is boiled, so the shortest cooking keeps it both green and lively, which is the entire point of the soup.
- Take it off the heat, stir in the lemon juice, and grind in the black pepper. The lemon lifts the peppery cress and finishes the soup in place of salt. Serve hot, with more black pepper at the table.
Nutrition
Estimated per serving: 120 calories, 4 g protein, 4 g fiber, 45 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.
