Measure out all of your spices in advance to save stress & time while you are cooking them. This will ensure you can enjoy the cooking process and avoid burning these delicate spices.
Measure the mustard & cumin seeds & set aside together.
Combine the coriander, garam masala, curry, turmeric, cayenne, & 1 tsp salt and set aside together. Chop the onions & potatoes, and mince the ginger.
In a large pan, heat the olive oil on medium heat until hot, about 1 minute. Add the mustard seeds and cumin seeds & cook, stirring for about 1 minute, or until the mustard seeds are popping.
Add the chopped onion & ginger and cook, stirring for 5-6 minutes, until the onion is translucent.
Add the remaining spices & minced garlic to the pot & cook for another 1-2 minutes, until fragrant (be sure to stir the whole time to avoid burning).
When the spices are smelling wonderful, add the lentils, potatoes, tomato puree, coconut milk, stock, & the last 1 tsp salt & stir well. If you like crunchier carrots add them after about 30min - otherwise you can add it now.
Cover with a lid & bring to a gentle boil over medium-high heat. Cook at a gentle simmer with the lid on for 40-45 minutes, until the lentils are soft, & the flavours are well incorporated.
Just before serving, add the spinach in batches & cook for a further 5 minutes.
Serve with plenty of ground black pepper & freshly chopped cilantro, (Optional)
This curry (like most curries) will taste even better the next day and in the days following, so make a batch and enjoy it with naan bread