Put the prepared potato chunks into a large saucepan with enough salted water to take the pasta later, and bring to the boil.
Cook the potatoes until tender, about 20 minutes, then add the pasta. Check the packet cooking instructions, and at about four minutes before the end of the specified cooking time, add the green beans. If you are using artisanal egg linguine, which takes less time, you will need to alter your strategy.
While this is bubbling away, whiz the ingredients for the pesto in a food processor.
Before you drain the saucepan, remove and reserve about 250ml of the cooking liquid.
Tip the drained potatoes, beans and pasta back into the dry pan.
Add the pesto from the processor and enough cooking water to give a runny sauce that coats the strands of pasta as you work it through with a fork or pasta claw. Serve immediately.
Make ahead note:
The pesto can be made two to three days ahead. Make the pesto using only 50ml olive oil and transfer to jam jar or airtight container. Carefully pour the remaining oil over the top so that surface of pesto is completely covered with oil. Store in fridge. Leave to stand at room temperature about 30 minutes before stirring and using.
The pesto can be frozen for up to three months in airtight container. Make the pesto and cover with a layer of oil, as above. Defrost for 2â€“3 hours at room temperature and stir before using.
Recipe from Nigella: Kitchen by Nigella Lawson (published by Chatto & Windus).