Dal.
In Leh, at 3 500 m, water boils at about 88 °C. A pot of chana dal that takes an hour in Delhi would take two and a half there — unless it goes into a pressure cooker.
Dal means both the pulse — lentils, peas and beans, usually hulled and split — and the soupy dish cooked from it. The everyday dals differ in size and toughness: red masoor and yellow moong dal are small and soften in 15–20 minutes of simmering; toor (pigeon pea) dal takes about 30–40; chana (split chickpea) dal an hour or more; whole urad, rajma and chickpeas, soaked overnight, an hour and a half or longer (XX.8). Cooked until they collapse, they are whisked smooth with turmeric and salt and finished with a tadka (XXIX.2). Dal and rice together give a complete protein, the reason for their partnership across South Asia.
Softening is a reaction whose rate climbs with temperature: pectin breaks down and starch gelatinises faster the hotter the water (XX.2). A pressure cooker at about 100 kPa above atmospheric pressure raises the boiling point to about 120 °C (III.4), cutting the time several-fold — Indian cooks count it in "whistles" as the weight lifts and releases steam. At high altitude, where the boiling point falls (III.3), open-pot cooking becomes very slow, and the pressure cooker is a necessity. Kidney beans (rajma) must boil hard for at least 10 minutes before slow cooking, to destroy their lectin (XX.8). The workshop cooks dal.
Below: the minutes to cook the dal you choose in an open pot or a pressure cooker (about 100 kPa gauge) at the altitude you choose: boiling point from the standard atmosphere and steam tables, cooking time scaled from sea-level practice by the course's vegetable-softening kinetics.
- Know the common dals and their times.
- Use a pressure cooker.
- Cook pulses at altitude.
- Finish dal with a tadka.
Hotter water, softer dal
Chana dal that takes 60 minutes in an open pot at sea level takes about 153 at Leh, where water boils at 88 °C — but only about 20 in a pressure cooker there. At sea level a pressure cooker brings toor dal from 35 minutes to about 8: the "three whistles" of Indian kitchens, plus the time to come up to pressure and down again. The softening slows steeply as the temperature falls, which is why mountain cooks rely on pressure.
Everyday toor dal for 4: rinse 200 g toor dal until the water runs clear; pressure-cook with 700 mL water, ½ tsp turmeric and a few drops of oil (to keep foam down) for 3 whistles, then let the pressure fall naturally; open, whisk smooth, add salt and simmer, loosening with hot water to a pourable soup. Tadka: heat 2 tbsp ghee, add 1 tsp cumin, then 2 sliced garlic cloves until golden, 1 dried chilli and a pinch of asafoetida, pour over; finish with lemon and coriander. Without a pressure cooker, simmer covered about 40 minutes, stirring now and then. For rajma: soak overnight, discard the water, and boil hard 10 minutes before simmering or pressure-cooking (XX.8).
Cook the same weight of toor dal in a pressure cooker and in an open pot. Time each from cold to soft.
Terms
- Dal
- Split pulses, and the dish cooked from them.
- Toor / masoor / chana / moong
- Pigeon pea / red lentil / split chickpea / split mung.
- Whistle
- A pressure cooker venting steam: Indian recipes count time by them.
- Rajma
- Kidney beans: boil hard 10 minutes first.
Sources
- ISO 2533:1975, Standard Atmosphere (the troposphere barometric formula).
- IAPWS, Revised Release on the IAPWS Industrial Formulation 1997 for the Thermodynamic Properties of Water and Steam (IAPWS-IF97), region 4 (saturation).
- A teaching value chosen for the course: the right order of magnitude and shape, not a measurement of a particular food.