1. Place the potatoes in a large pot of water, and add 1 tbsp salt. Bring to boil, then lower heat and simmer until cooked – they should not resist when pierced with a knife. Don't worry if the skins of some burst. Drain well. 

2. Make the honey mustard dressing by shaking all ingredients in a jar.

3. While still hot, gently press down on a potato with a spoon or fork (or tea towel-covered hands), so it bursts open but retains its shape. Place it in a large serving bowl and repeat. 

4. Add the onion, pour over the dressing and gently toss – it looks nice and rustic if some fall apart, though in a perfect world, most would hold together. Set aside for at least 30 minutes (even the next day is great!) to let the dressing soak in. 

5. Just before serving, sprinkle with thyme leaves and give them another toss. Serve slightly warm or at room temperature – never fridge-cold.

This recipe features in Nagi Maehashi's festive spread for $20 a head.