The fashionista’s greatest joy, it always seems to me, is an outfit that can be up- and downgraded; ‘for day and night’, I think is the phrase. I have never understood this concept with clothes (do people really change at the end of the day, after work, to go out in the evening, unless there’s a dress code?) but I do see its value in food.

A sauce for pasta, or a base leaf mixture for a salad that can be added to, in lots of different ways, depending on what you have, seems like a very sensible way to improve your repertoire without much effort.

This summer’s version of a perfect outfit comes from Rachel Roddy’s Five Quarters which, along with her second book Two Kitchens, is currently my favourite. I rarely insist that a cookbook is indispensable but, to me, this one is; it’s so user-friendly and accessible that I think it is especially helpful to both anyone who wants to learn to cook from scratch, since her recipes are very simple and short on ingredients, but also someone who wants new ideas that slot like old friends into the day-to-day. I’d be happy to cook from just the two of them all year, and I bet I’d still be finding new things after that.

Here is a brilliant example of what Roddy excels at: combining three pretty standard and easily-bought ingredients, green beans, potatoes and mint and making them completely new, at least to me. I’ve made this about three times now, as it is, for a side dish, and it’s wonderful. I especially love that you make it in advance and there is no last-minute faffing before you serve it.

What turns it into a real performer is that you can add to it: with some soft-boiled eggs, this becomes lunch or dinner; anchovies and black olives as well and you have an Italian take on salade Niçoise. At a push it could also be a starter. Also, in its original form it ticks all the current hipster boxes: vegetarian; vegan; gluten- and dairy-free. When a friend asked me for a salad that could happily be made in advance, travel across country on a hot day to be eaten on a camping trip, I didn’t hesitate to suggest this. She thought it was delicious, too, even after its journey. If that’s not the perfect ‘outfit’ for all occasions, I don’t know what is. See, day to night!

So, if you haven’t discovered Roddy’s books yet, or her excellent column in the Guardian, you are in for lots of treats. Try this and you will see what I mean.

Potatoes and green beans (adapted from Five Quarters)

Makes enough for 4 as a side, two as a main with additions

Cupboard (or things you may already have)
extra-virgin olive oil
red wine vinegar (in the recipe it is optional, but I rather love it)
good salt

Shopping list
large waxy potatoes (Charlottes are good, as are my favourites, Rattes), 4, or 8 small ones
fine green beans, 500g
some small, fresh mint leaves

How to
1. Wash but don’t peel the potatoes then cook them in boiling, salted water until done (the time will depend on their size). Drain and leave to cool.

2. Meanwhile, top and tail the beans then cook them in boiling, salted water until done (again, the time will depend on their size).

3. When the vegetables are cool enough to handle but still warm, put the beans in a bowl, peel the potatoes (the skins may just come off in your hands so you might not need a knife) and roughly break the potatoes over the top of the beans (again, I do this with my hands).

4. Sprinkle the mint leaves over the potatoes then dress everything with sea salt, some olive oil and red wine vinegar. Toss together gently (again, hands are best!). Taste and add more oil, salt or vinegar as required. Leave to stand for a good while (at least 30 minutes, but a few hours won’t hurt) before serving.