Sip and Feast cooks this Italian lentil soup on the hob in a Dutch oven, simmering for 30 to 45 minutes until the lentils are tender. It adapts very naturally to the slow cooker because it is already a long, gentle simmer. The sofrito of onion, carrot and celery is sweated on the hob, the tomato paste is fried until it takes on colour, then everything moves to the slow cooker with the lentils, water, oregano and Parmigiano rinds. Spinach goes in right at the end to wilt, then the soup is finished with salt, pepper and whatever topping you prefer: olive oil and Parmesan, Greek yoghurt, or red wine vinegar.
Slow cooker notes: Original is a hob simmer in a Dutch oven. Adapted to the slow cooker by keeping the sofrito sweat and the tomato paste fry on the hob (the source is firm that both steps build the flavour, and notes you could skip them and just boil it all together but you lose depth). Everything then transfers to the slow cooker for a Low 6 hour or High 3 hour cook. Baby spinach still goes in right at the end to wilt. Water quantity kept the same (8 cups) because lentils absorb a lot and the slow cooker loses very little to evaporation; top up if it looks dry.
Ingredients
- 60 mlextra virgin olive oil, to coat the bottom of the pan
- 1medium onion, diced
- 2celery ribs, diced
- 2medium carrots, diced
- 85 gtomato paste
- 225 gdatterini tomatoes, crushed by hand or broken with a spoon
- brown lentils, spread out and checked for stones or bad lentils
- 2Parmigiano Reggiano rinds, whole rinds, saved from grated blocks
- 1900 mlwater
- 1 tspdried oregano
- 1.5 tspkosher salt, added at the start
- 225 gbaby spinach (add late)
- 1.5 tspkosher salt, added at the end to taste (add late)
- 1 tspblack pepper (add late)
- extra virgin olive oil, a potent drizzle (add late)
- grated Parmesan (add late)
- Greek yoghurt (add late)
- red wine vinegar (add late)
- crusty bread (add late)
Method
Heat the olive oil in a heavy pan or Dutch oven on a moderate heat (about a four out of ten). Add the diced onion, carrot and celery at the same time and let them sweat for 10 to 12 minutes, without taking much colour, until very soft and sweet.
~13 minStir in the tomato paste and fry it out for about 5 minutes, stirring constantly so it does not burn. The paste should darken and take on colour. If it looks like it is catching, lower the heat or add a touch more oil.
~5 minSpread the brown lentils out on a tray and check for stones or any bad lentils, then tip them into the pan. Add the crushed datterini tomatoes (break them up with a spoon, careful of the squirt) and stir to coat everything in the paste.
~3 minTransfer everything to the slow cooker. Add the Parmigiano rinds, the 8 cups of water, the dried oregano and 1.5 teaspoons of kosher salt. Use some of the water to deglaze the pan, scraping up any caramelised bits from the bottom, and tip that into the slow cooker too.
~3 minCover and slow cook on Low for 6 hours, or on High for 3 hours, until the lentils are tender but still hold a little texture (you don't want them turned to mush, but no hard pieces either). If it looks dry, top up with a little more water.
~360 minStir in the baby spinach. It will look like too much but wilts down in about a minute, especially if you bury it under the lentils.
~2 minTaste and finish with the second 1.5 teaspoons of salt and about a teaspoon of black pepper. Add a touch more dried oregano if you like. The Parmigiano rinds can be fished out (they are edible, or a treat for a dog).
~2 minLadle into bowls and finish however you fancy: a potent drizzle of good olive oil with grated Parmesan and crusty bread, a spoon of Greek yoghurt for tang, or a small splash of red wine vinegar.
~2 min