Bring a large saucepan of salted water to the boil. Add beans and cook for 5 to 6 minutes or until just tender (see shortcut). Drain and refresh under cold water. Drain again and pat dry with paper towel. Place beans on a plate. Cover and refrigerate until required.
Preheat oven to 180°C. Place walnuts on a baking tray. Roast for 5 minutes or until golden and crisp. Transfer to a board. Allow to cool for 5 minutes. Roughly chop.
Whisk oil and 1/3 cup lemon juice in a jug. Add walnuts, capers, parsley, onion and sugar. Season with salt and pepper. Pour caper salsa over beans and serve.
Notes & Tips
The dressing is to die for and would also work well with fresh asparagus.