Potato pancakes and rösti

Why

Raw potatoes are roughly three quarters water; grated potato that hasn't been squeezed cools the fat in the pan, the pancake steams instead of frying, the crust forms slowly, and meanwhile the mixture soaks up more fat and falls apart more easily. The squeezed-out juice leaves white potato starch settled at the bottom, which is worth returning to the batter because it binds the pancakes. Grated potato turning grey is enzymatic browning: an enzyme from the damaged cells oxidises phenolic compounds in contact with air; it is harmless and only spoils the look, and working quickly, keeping things cold or mixing in grated onion slows it down. Swiss rösti is made from raw potatoes or from potatoes boiled in their skins, classically the day before, which are less sticky and hold their shape better; floury potatoes suit it less well. The pan must be hot enough for the pancake to sizzle at once, but not so hot that the outside blackens before the potato inside is cooked through.

How to do it

• Grate the potatoes just before frying and use them straight away; don't leave the finished mixture standing.
• Squeeze the grated potato in a cloth or sieve, let the juice settle briefly and return the starch from the bottom to the batter.
• For potato pancakes, heat a layer of oil until a drop of batter sizzles hard at once; spread the pancakes thin and fry until golden, not dark brown.
• Fry only as many pancakes as fit without touching; let the oil heat up again after each batch and top it up.
• For rösti, use clarified butter or butter with a little oil; plain butter burns easily during longer frying.
• Drain the finished pancakes on a rack or kitchen paper so they don't sit in fat.

If it goes wrong

If the pancakes fall apart, stir the settled starch, a spoonful of flour or an egg into the batter and fry a test one. Make pancakes that are dark outside and raw inside thinner next time and fry them over gentler heat; finish the ones already fried for a few minutes in the oven. Batter that has turned grey is edible, the pancakes will just be darker.