Lentil and sweet potato curry

This recipe is a lovely vegan curry (providing you use a vegan curry paste and stock cube - my Patak's paste used to include lactic acid, but the jar I currently have appears not to. I'm not sure if the other acids in it come from non-vegan sources. I'm always shocked by how many animal-based ingredients turn out to be in unexpected products). It tastes so good even the confirmed carnivores in my life love it. The only vegetables in it that I can actually grow (at least until I get a greenhouse) are the onions, but you can't have everything!

Preparation and cooking time: about 60 minutes. Ideally put lentils in to soak an extra 20 minutes before you start.

Ingredients

150 g dried red lentils
2 medium/large sweet potatoes
c. 4-5 tbsp. olive oil
1 tsp. mild chilli powder
1 green pepper
1 red pepper
1 large onion
2 tsp. mustard seeds (brown look better, yellow are easier to find, both taste the same)
2 tbsp. of Patak’s mild curry paste
450ml of boiling water
1 vegetable stock cube (I used Kallo)
1 tin of black beans
1 handful chopped fresh or frozen coriander (optional)

1. Put lentils in a bowl of water and leave them to soak (ideal total soaking time: 45 mins, so best to put in about 20 mins before starting, but right at the start is enough time if in a rush).
2. Preheat the oven to 190°C/fan 170°C/gas 5.
3. Peel sweet potatoes and chop into large bite sized chunks (c. 2 cm³). Place in a shallow roasting tin and drizzle with a generous quantity of olive oil (around 3-4 tbsp. - the more you put in the better the mouth feel).
4. Sprinkle the sweet potato chunks with chili powder (about 1 tsp.), then stir to coat evenly in chili and oil. Put in oven for 15 mins.
5. Chop peppers and onions into large bite-sized chunks, but keep separate from each other.

6. After the sweet potatoes have done their first 15 mins, add the peppers in with the sweet potatoes, stir, then return sweet potatoes and peppers to oven for another 25 mins.
7. Heat 1-2 tbsp. of olive oil in a large saucepan on a high heat. Add the 2 tsp. of mustard seeds, cook on a high heat with the lid on the pan till the seeds pop (like popcorn) or for 5 mins, whichever is shorter. Then add the onion and fry for c. 4 minutes until soft.
8. Stir in the curry paste, then stir in the lentils.
You can get the curry paste from Sainsbury's, or in case you can't find it, here's a photo of the ingredients so you can look for something similar or put your own spices together (I've tried it with other curry pastes and it just doesn't taste right).

9. Add the boiling water. Add the vegetable stock cube and stir. Simmer for c. 15-20 mins until lentils are tender (if you use 100% tinned lentils, you need only simmer for 5 mins).
10. Chop one handful of coriander if using fresh coriander.
11. Stir in the tin of black beans.

12. Stir in the roasted sweet potatoes and peppers and all the oil from the roasting tin into the lentils. Stir in the chopped fresh or frozen coriander and keep on hob till everything is warmed through.
13. Serve on its own or with warm naan bread or chapatis.