Heat your oven to 180°C/Fan 160°C/Gas 4. Add 1 tsp each coriander and cumin seeds to a dry pan. Place on a medium heat and toast for 2 mins till the seeds smell aromatic and start popping. Tip them into a mortar and grind them with a pestle, or use a small bowl and a jam jar to crush them. Set aside.
Peel and finely chop the onion, carrot, parsnip and half the swede. Warm 2 tsp olive oil in the pan and add the chopped veg. Season with salt and pepper. Cook over a medium heat for 10 mins, stirring occasionally, till the veg have started to soften and brown (but only a little – if they start to colour too much, turn the heat down). If the veg start to stick, add a splash of water to the pan.
While the veg sweat, halve the pepper. Scoop out the seeds and white pith. Finely chop it. Tear the kale leaves off the thick stalks and pop them in a bowl. Set aside.
Add the ground cumin and coriander to the pan. Stir in the pepper. Tip in the chopped tomatoes. Fill the tin with water (approximately 400ml) and add that too. Add a pinch of chilli flakes, adding a smuch or as little as you like (they're spicy). Give everything a good stir, then cover and simmer for 15 mins till the veg are tender. Stir a couple of times while it's cooking.
Add 1 tbsp olive oil to the kale with the tahini and a good pinch of salt and pepper. Turn the kale over and over with your hands to make sure it all gets coated with oil and seasoning, giving it a good squeeze.
Spread the kale out on one large or two medium baking trays. Bake in the oven for 10 mins till the kale is crisp but not too charred.
Taste the vegetable chilli. Add a pinch more salt and pepper if you think it needs it. Serve in warm bowls with the kale chips.