Apple, Fennel and Celeriac Slaw with Mustard Vinaigrette

Ingredients

• 1 small celeriac (about 500g), peeled
• 1 large fennel bulb, fronds reserved
• 2 Granny Smith apples
• 1 lemon, juiced
• 2 spring onions, finely sliced
• 2 tbsp wholegrain mustard
• 1 tbsp Dijon mustard
• 3 tbsp cider vinegar
• 1 tsp runny honey
• 6 tbsp extra virgin olive oil
• 1 small shallot, very finely diced
• sea salt and black pepper
• 20g flat-leaf parsley, leaves picked and roughly chopped
• 10g tarragon, leaves picked
• reserved fennel fronds

Method

1. Squeeze the lemon juice into a large mixing bowl — this is your holding tank. Apple and celeriac both oxidise within minutes of being cut, so everything gets tossed through the lemon juice as it's shredded, not after.
2. Peel the celeriac thoroughly with a knife — the skin is too gnarly for a peeler — and cut into quarters. Run it through a mandolin on the julienne setting, or stack thin slices and cut into matchsticks by hand. You want pieces fine enough to bend, not woody chunks. Drop straight into the lemon bowl and toss to coat.
3. Trim the fennel, halve through the root, and cut out the tough core. Shave on the mandolin as thinly as you can — almost translucent. Thick fennel stays squeaky and aggressive; thin fennel goes silky and sweet. Add to the bowl.
4. Quarter and core the apples (don't peel — the green skin is the colour of the dish). Cut into matchsticks the same size as the celeriac. Toss through the lemon immediately — any apple not coated within a minute or two will start browning at the edges.
5. Add the sliced spring onions and toss everything together with your hands so the lemon juice reaches every surface. Season the vegetables with a generous pinch of salt now — it draws a touch of moisture out and starts the seasoning from the inside.
6. Make the vinaigrette: in a jam jar, combine both mustards, cider vinegar, honey, diced shallot, a good pinch of salt and plenty of black pepper. Add the olive oil, lid on, shake hard for 20 seconds until thick and emulsified. Taste — it should be sharp and punchy, almost too punchy on its own. The slaw is mild and sweet, so the dressing has to carry.
7. Pour two-thirds of the dressing over the slaw and toss thoroughly. Let it sit for 5 minutes — the celeriac and fennel soften slightly and drink in the dressing without going limp. Taste, season, taste again. Adjust salt and add more dressing if it needs it — do it now, not at the table.
8. Just before serving, scatter over the parsley, tarragon leaves and reserved fennel fronds and toss once more. Don't add the herbs early or they'll bruise and darken in the acid. Pile the slaw onto a serving platter alongside the cold roast pork, ham or grilled mackerel, with cornichons, torn hunks of baguette or sourdough, and an extra spoon of wholegrain mustard on the side.