Kasseler Grüne Soße

Ingredients

Equipment Needed

• •Salad spinner or clean kitchen towels
• •Sharp chef's knife
• •Mixing bowl
• •Small whisk or fork

Instructions

1. 1

   Cook eggs and potatoes

   Put the potatoes in cold salted water and bring them to a gentle simmer until a knife goes through cleanly, 20 to 25 minutes. Starting them cold lets the centre cook with the skin, so the outside doesn't split before the middle is done. Lower the eggs into simmering water for 9 minutes, then put them straight into cold water; that stops the cooking and keeps the yolk firm without the dry green edge.

2. 2

   Wash and dry herbs

   Swish the herbs in cold water, lift them out of the bowl, and dry them hard in a salad spinner or clean towel. Pour the water away, not over the herbs again, because the grit sits at the bottom. Wet herbs thin the Schmand and carry the flavour into water instead of fat, which is how a green sauce turns pale and slack before it reaches the table.

   Strip thick borage stems and any coarse parsley stems. Tender chive, dill, and burnet stems can stay because they carry flavour and chop cleanly.
3. 3

   Chop by hand

   Chop the herbs by hand until they are fine enough to fold through the sauce but still visible. Kassel wants the herbs coarse and clear, not a smooth green cream. A blender bruises and warms the leaves, and the sauce tastes flat and bitter instead of clean. No chervil, no cress here; that is Frankfurt's argument, and this is North Hesse.

   Cut the chives last with a sharp knife. Saw at them with a dull blade and they weep onion juice into the board before the sauce ever sees them.
4. 4

   Build the base

   Peel two eggs for the sauce. Mash their yolks with the mustard, vinegar or lemon juice, sugar, and a small pinch of salt, then whisk in the Schmand and yogurt until smooth. The yolk gives body, the fat carries the herbs, and the acid keeps the dairy awake. Chop the two whites small and fold them in; the little pieces belong in the sauce, not in the bin. Weggeworfen wird nichts.

5. 5

   Fold and rest

   Fold the chopped herbs into the Schmand base with a spoon, not a whisk, so the herbs stay in pieces instead of turning the dairy muddy. Cover and chill for 20 minutes. Das braucht seine Zeit, even for a cold sauce: the fat takes the herb oils and the sharp edges settle. Do not salt hard yet, because salt pulls water from cut herbs and thins the sauce.

6. 6

   Serve cold

   Drain the potatoes and let their surfaces dry for a minute, because water on the skin dilutes the first spoonful of sauce. Peel and halve the remaining eggs. Taste the Grüne Soße, then finish with salt, white pepper, and a spoon of buttermilk only if it needs loosening. Spoon it cold over the warm potatoes and eggs. Würzen, Fett, Salz zum Schluss.

Chef Tips

• •Dried herbs don't belong here. This sauce is the first-green bowl of the year, and a packet of dusty leaves gives you colour without life. Nicht aus dem Glas.
• •If Schmand isn't sold where you are, use full-fat sour cream mixed with a spoon of crème fraîche. Low-fat dairy turns chalky and watery once the herbs and salt work on it.
• •Use young borage leaves and the small amount given. If you're pregnant, nursing, or serving very small children, leave borage out and replace the weight with parsley and dill.
• •Make the sauce a few hours ahead, not days ahead. The herb flavour settles after a short rest, then dulls by the next day. That is not failure. That is chopped spring behaving like chopped spring.

Advance Preparation

• •Boil the eggs up to 2 days ahead and keep them refrigerated in their shells; peeled eggs dry out and pick up refrigerator smells.
• •Wash and dry the herbs up to 6 hours ahead, then wrap them in a barely damp towel and refrigerate. Chop them only when you are ready to mix, because cut herbs lose their snap.
• •The finished sauce can be made 4 to 6 hours ahead and kept cold. Season finally just before serving, because salt keeps pulling water from the herbs as it sits.

Frequently Asked Questions

Nutrition Information

1 serving (about 425g)