Step 1

Cook the potatoes in a large pan of boiling salted water for 15-20 minutes or until tender. Drain and cool.

Step 2

Cook the butter and onion in a large frying pan for 5 minutes or until turning translucent. Add the garlic and fry for another 5 minutes. Add the mustard seeds and coriander seeds, and fry until starting to smell fragrant. Add the dijon mustard and juice of 1 lemon and mix. Transfer to a bowl.

Step 3

Tip the cooled potatoes onto a clean worksurface and use the flat side of a knife to lightly squash each one. Fry the potatoes in a little more oil in a large non-stick frying pan for 10-15 minutes or until starting to crisp up. Tip onto kitchen paper to drain.

Step 4

In the meantime, make the aïoli. Put the egg yolks, garlic, lemon juice and plenty of seasoning in a small blender, and whizz until smooth. Slowly drizzle in the olive oil while still blending on a low speed, until it emulsifies, thickens and is smooth.

Step 5

Put the crispy smashed potatoes into a bowl and mix in most of the onion butter and sliced radishes.

Step 6

Spread the aïoli across a platter and pile the potatoes on top. Finish with a drizzle of the remaining butter and lots of fresh dill.