1) Start the flavour base
Heat olive oil in a large pot on medium heat.
Add onion and cook 5–7 minutes until soft.
Add garlic and cook 30 seconds.
2) Add veg + spices
Add carrots + celery (and courgette if using). Cook 3–4 minutes.
Stir in cumin, turmeric (optional), pepper, salt (and chilli/paprika if using). Cook 30 seconds.
3) Add lentils + stock
Add rinsed lentils and stir to coat in the spices.
Pour in stock/water and bring to a boil.
Reduce to a gentle simmer.
4) Simmer until soft
Simmer 18–25 minutes (red lentils) until the lentils and veg are very soft.
Stir occasionally so nothing sticks.