Combine the sunflower oil with the walnut oil.

In a mixing bowl, whisk together the egg yolk, lemon zest and orange zest.

Gradually add the oil mixture while whisking continuously until emulsified.

Stir in the lemon juice and orange juice, then season with salt and pepper.

Pass through a fine sieve.

Transfer to a piping bag and store in the refrigerator until needed.

Cut the fennel, celeriac trimmings and onion into small mirepoix.

Sweat them with half of the butter until fragrant.

Add the chicken stock and simmer until reduced to 200 ml. After straining, you should obtain about 150 ml.

In another pan, melt the remaining butter and add the flour to form a roux.

Add the strained stock while stirring vigorously until the mixture thickens.

Incorporate the orange zest, Thai basil and pan-fried celeriac brunoise.

Allow the mixture to cool.

Shape into balls of approximately 2 cm diameter and place in the freezer until firm.

Once frozen, bread with plain flour, egg and fine breadcrumbs, then return to the freezer.

Bread a second time using only egg and breadcrumbs, and freeze again until needed.

Deep-fry at around 170°C for approximately 2 minutes, until golden brown.

Serve warm with the walnut and orange mayonnaise.