Adapted from Sirocco by Sabrina Ghayour (Clarkson Potter, 2015). Here's what Ghayour says of the recipe:
“This is a hearty dish that we Iranians enjoy in the cold and snowy winters of Iran, although I first ate it in Switzerland when my aunty Nini cooked it for me. Her version, which I have been cooking for more than 20 years, is another great one-pot dish. (It differs in that the curry powder is slightly different.) The amount of flavor, considering how few ingredients are involved, always surprises me. It gets better and better the longer you keep it, as the flavors intensify. You can eat it as a soup, or make it thicker for a stew. Serve with crusty bread and enjoy."
She has you mix the tomato paste, curry powder, and salt with a bit of water, but I found the stew more flavorful without it. —Ali Slagle
Heat a saucepan over medium heat. Add the oil and fry the onion until translucent. Add the lentils and stir for 1 minute, then stir in the tomato paste and curry powder, and season with salt. Stir well for about a minute, until the ingredients are evenly mixed and fragrant.
Then, in stages, stir in a few ladlefuls of hot water at a time, stirring well and allowing each ladleful of water to be thoroughly absorbed by the lentils before adding the next. Once all the water has been absorbed, taste the lentils to check you are happy with the texture and that they are cooked thoroughly. If not, add another ladleful or two of water.
Store in an airtight container in the fridge for up to 5 days.