Rinse the potatoes and place in the pan and cover with cold water. Add a teaspoon of salt. Cover with the lid and bring to the boil
If your potatoes are lots of different sizes, or you just need to cook very quickly, you can cut them into smaller pieces.
Whilst the potatoes are cooking, cut the green beans to a similar length to the pasta.
Check for 'done-ness' - depending on the size they'll be ready in anything between 20 and 30 minutes.
When they are soft, remove from the boiling water with a slotted spoon/tongs and place in the bowl. Do not drain the water. Stir pesto through the potatoes whilst warm.
Get the water boiling again and cook the pasta; check it 2 minutes before the packet suggests as sometimes they aren't quite accurate.
When the pasta is done, again remove with a slotted spoon and add to the pesto and potatoes.
Boil the beans in the potato pasta water. Remove when done, around 4 minutes.
Add more pesto if you wish (I like a lot) and serve.