Trim the Brussels sprouts, removing any damaged outer leaves, then cut them in half.
Blanch the sprouts in boiling, lightly salted water for 3 minutes, then drain well.
Cut the bacon into thin strips.
Heat a little oil in a large frying pan over medium heat. Add the sliced onion and bacon and cook until the onion is soft and the bacon begins to crisp.
Add the blanched sprouts and apple cider vinegar. Stir gently and cook until the sprouts are golden and caramelised.
Add the green beans and a small splash of water. Sauté for 3–5 minutes, until the beans are just tender.
In a separate dry pan, lightly toast the cashew nuts until golden.
Add the nuts to the sprouts, toss everything together and season to taste.
Serve warm, or reheat gently just before serving.