Put a dry wok or deep frying pan over a medium heat and add 1 tsp coriander seeds. Toast for 2-3 mins, shaking the pan occasionally, till the coriander seeds are popping and aromatic. Tip into a mortar and roughly crush them with a pestle, or use a small bowl and the bottom of a jam jar or rolling pin.

Peel and finely slice the onion. Roughly chop the tomatoes. Scrub the Jersey Royals and quarter or halve them, depending on how big they are. Peel and grate the garlic and ginger. Finely chop the chilli, flicking out the seeds and pith for less heat.

Put the wok back over a high heat and warm for 2 mins. Add 1 tbsp oil and the red onion. Stir fry for 5 mins till a little browned and softened.

Add the tomatoes to the pan with the garlic, ginger and chilli. Stir fry for 5 mins till the tomatoes start to break down and become pulpy.

Add the potatoes to the pan. Tip in the ground coriander. Add 1 tbsp Thai green curry paste and the peanut butter. Stir to mix everything together. Pour in the coconut milk and add 200ml boiling water to the pan. Pop a lid on the pan (or use a baking tray to cover the pan if you don't have a lid) and bring the curry to the boil. When it's boiling, turn the heat down and simmer for 10 mins till the potatoes are tender when pressed with a fork.

Roughly chop the spinach. Stir into the curry to wilt it. Squeeze in the juice from the lime. Finely slice the mint leaves and stir half into the curry. Taste the curry and add a pinch of salt if you think it needs it.

Ladle the curry into 2 warm bowls, top with the last of the mint leaves and serve.