Charred Pointed Cabbage in Harissa Tomato with Tahini and Sumac Onions

Salt on a cut cabbage face pulls water out in a few minutes. That water holds the surface near 100 °C, so the face steams and does not brown. Browning needs the surface above about 140 °C.

Pointed cabbage holds more free sugar than white cabbage, so a dry face browns fast and deep. The weight presses the loose leaves flat against the pan. This gives an even crust instead of brown patches.

Salt the faces after the sear.

Cut cabbage releases isothiocyanates, which give the sharp mustard taste. Heat stops the enzyme that makes them. Long wet cooking then breaks sulfur compounds down to dimethyl trisulfide and hydrogen sulfide. These give the smell of overcooked cabbage.

Pointed cabbage has thin cell walls and becomes tender fast. Stop when the knife meets a small resistance in the core. Keep the charred faces above the liquid so the crust stays dry.

Sumac is sour from malic acid. Its fruity smell comes from volatile compounds that heat drives off. So it goes on the onions and on the finished dish, and never into the pan.

Sumac and red onion both hold anthocyanins. These pigments are brightest at low pH. The lemon juice drops the pH, so the onion turns bright pink. Squeezing breaks the onion cells so the acid gets in and softens the raw sulfur taste.