Put a large pot or pan on your hob, add the vegetable oil and heat on a low/medium heat
Add the chopped onion, garlic and ginger (you can also add fresh chillies at this point if you want to) and cook for around 5 minutes until softened and the onion has started to go translucent
Add the curry powder and garam masala, stir everything together and cook for about a minute
Pour in the chopped tomatoes, and add the tomato puree. Then add the coconut milk - only add the thick white top layer from the can, leaving the watery bit behind
Then in a small bowl, mix the cornflour with a glug of the coconut water and stir until combined. Then add to the curry
Bring the curry to a simmer and simmer gently for 10 minutes until thickened
Add the spinach, if using fresh spinach stir it in to the curry and cook for a few minutes until it has wilted down
Add the lentil and stir into the curry, keep on the heat for around 5 minutes so the lentils can warm up in the sauce
You can add some salt and pepper at this point if you like, to taste
Serve the curry immediately with rice, naan, yoghurt, or your other favourite accompaniments
You can freeze fully cool leftovers in airtight containers or freezer bags, or store in the fridge for 2-3 days and reheat in the microwave or in a pan on a low heat
Notes
I use white onion in this curry, but I did make it once with red onion when I'd ran out of white onion, and it was just as tasty!
I use a mix of mild and medium curry powder when I make this, but if you like it spicy then you can use a hot curry powder instead.
Garam masala is a spice blend containing coriander seed, cumin seed, fennel seed, dried ginger, dill seed, cloves, and celery seed. You can use individual spices if you prefer, but this spice blend is such a handy way of adding lots of flavour quickly.
You will need tinned green or brown lentils for this recipe, I have not tried this recipe with dried lentils.
Although I provide cup measurements, I highly recommend weighing your ingredients out using digital kitchen scales. It is the most accurate way to measure ingredients and will ensure the best results. Digital scales are very low cost and can be purchased for around £12 ($16.50).
For teaspoon (tsp) and tablespoon (tbsp) measurements, please use measuring spoons and not the type of spoons you eat with. Again this will ensure accuracy and provide the best results.