Peel the onions and thinly slice them. Trim the leaves off the cauliflower (see our tip, below, for what to do with them), then slice the cauli into florets. Thinly slice the stalk. Scrub the potatoes and chop them into small, bite-sized chunks. Roughly chop the tomatoes. Set aside.

Make the curry paste: separate the coriander leaves and stalks (save the leaves for later). Add the stalks to a food processor. Peel and chop the garlic and ginger, and add those. Trim the chilli, if you’re using it, and add to the processor (you can leave it out for a milder curry, or scrape out the seeds and white pith for a little less chilli heat). Add 2 tsp each ground cumin, garam masala and turmeric. Add a good pinch of salt and pepper and 1 tbsp oil. Whizz into a paste. No food processor? Chop everything as finely as you can, grating the garlic and ginger, then stir into a slightly chunkier paste.

Pour 1 tbsp oil into a large pan and set it over a medium-high heat. Add the cauliflower to the pan and cook for 5 mins, stirring occasionally, till starting to brown. Scoop the cauliflower out of the pan and set aside on a plate.

Pour another 1 tbsp oil into the pan and add the onions. Fry for 5 mins, till softened. Stir in the curry paste and continue to cook for 3-4 mins. Add the potatoes to the pan and mix well with a wooden spoon. Cook for 10 mins, stirring often.

Add the cauliflower back into the pan with the chopped tomatoes and swirl in 300ml boiling water. Bring to a simmer, then cover the pan and cook for a further 20 mins, till the potatoes are tender and the sauce has thickened a little.

Tip the spinach into the pan and stir to wilt. Have a taste and add more salt or pepper if needed. Heap the curry onto plates and serve topped with the coriander leaves.