Frankfurter Grüne Soße
Frankfurt Green Herb Sauce with Eggs- Yield
- Serves 4 to 6 as a main course (about 2 1/2 cups sauce)
- Active
- 45 minutes
- Total
- 1 hour 15 minutes (including 30 minutes chilling)
- Difficulty
- Easy
The story
In Germany, Maundy Thursday is called Gründonnerstag, and in 2027 it falls on March 25. The origin of the name is disputed: one theory traces it to the Middle High German greinen, to weep, another to the green vestments worn on that day in the Middle Ages. Either way, the day is linked to green food, and many German families still eat spinach, herb soup or green sauce and no meat. In Frankfurt and the rest of Hesse that means Grüne Soße: seven herbs chopped very fine and stirred into sour cream, served with hard-boiled eggs and boiled potatoes. The seven are parsley, chives, chervil, sorrel, cress, borage and salad burnet. Its origin is unclear, but a cook at Frankfurt's Weißer Schwan inn mentioned an herb sauce in his cookbook in 1768. Today the city has a festival and a monument for the sauce, and herbs sold under the Frankfurt name must come at least 70 percent from the Frankfurt region, with no single herb above 30 percent. The season opens on Maundy Thursday and runs into May. Buy the herbs a day ahead, and serve two eggs per person.
Ingredients
- For the sauce:
- 7 oz mixed fresh herbs (parsley, chives, chervil, sorrel, cress, borage and salad burnet; about 7 small bunches)
- 3 large eggs
- 1 tablespoon medium-hot German mustard or Dijon mustard
- 1/2 teaspoon salt, plus more to taste
- 1/4 teaspoon freshly ground black pepper
- 1/8 teaspoon sugar
- 2 tablespoons sunflower or other neutral oil
- 1 tablespoon fresh lemon juice or white wine vinegar
- 1 cup (8 oz) full-fat sour cream
- 1/2 cup plain whole-milk yogurt
- For serving:
- 2 1/2 lb small waxy potatoes, scrubbed
- 1 tablespoon salt, for the cooking water
- 8 large eggs
Rarely sold in US stores. Use a few strips of cucumber peel or extra cress for its cucumber note; borage also grows easily from seed in a garden.
Use extra chervil and a little more sorrel. Burnet plants are sold at garden centers and some farmers markets in spring.
Look for it at farmers markets and specialty grocers in spring; otherwise use more flat-leaf parsley with a few tarragon leaves.
Sold at farmers markets in spring. If you cannot find it, add a handful of baby spinach and a little extra lemon juice.
Method
- Place all 11 eggs in a saucepan, cover them with cold water by 1 inch and bring to a boil over high heat. Lower the heat and simmer for 10 minutes, until the yolks are fully set, then move the eggs to a bowl of ice water for 5 minutes and peel them. Set 8 eggs aside for serving.
- Wash the herbs in several changes of cold water and spin them completely dry. Pull the leaves off the coarse stems of the parsley, chervil, sorrel, borage and burnet.
- Chop all the herbs very finely with a large knife or a mezzaluna, working in batches, and cut the chives into thin rings. You should have about 2 cups of loosely packed chopped herbs.
- Halve the 3 remaining eggs, press the yolks through a fine sieve into a mixing bowl and finely dice the whites. Stir the mustard, 1/2 teaspoon salt, pepper and sugar into the yolks, then whisk in the oil a little at a time, followed by the lemon juice.
- Whisk in the sour cream and yogurt until smooth. Fold in the chopped herbs and two-thirds of the diced egg white, then taste and add salt, pepper or lemon juice as needed.
- Cover the sauce and refrigerate it for at least 30 minutes so the flavors blend.
- Meanwhile, put the potatoes in a pot, cover them with cold water, add 1 tablespoon salt and bring to a boil. Simmer for 15 to 20 minutes, until a knife slides in easily, then drain. Peel them while warm if you like, or serve them in their skins.
- Halve the 8 reserved eggs. Spoon the sauce onto plates, set the egg halves and the hot potatoes beside it and scatter the remaining diced egg white over the sauce.
Note: The sauce is best on the day it is made, because the chopped herbs darken; keep it refrigerated for up to 1 day. Do not leave the sauce or the peeled eggs out of the refrigerator for more than 2 hours.
Buying tip: In Frankfurt the seven herbs are sold together as a ready-made Grüne Soße bundle. In the US, buy them separately: parsley, chives, cress and sorrel are easy to find, while chervil, borage and burnet usually come from a farmers market or a garden.