Rye Crisp with Mustard Butter, Caramelized Onion, and Pickled Radish

Slice the radish into thin coins, roughly 3mm thick. Pack into a heatproof jar or small bowl.

In a small saucepan, combine the white vinegar, white sugar, and salt. Bring to a gentle simmer over medium heat, stirring until the sugar dissolves completely, about 2 minutes.

Pour the hot vinegar mixture over the sliced radish. Let cool to room temperature, then cover and refrigerate for at least 30 minutes. The radish will soften slightly and turn a vivid pink. (These keep refrigerated up to 1 week.)

Place the softened butter in a small bowl. Add the mustard, chopped parsley, and white pepper. Stir vigorously with a fork until evenly combined and creamy.

Transfer to a small serving bowl or shape into a log on plastic wrap. Set aside at room temperature until ready to assemble.

Peel and halve the yellow onion, then slice into thin half-moons, about 3mm wide.

Melt the butter in a heavy skillet over medium-low heat. Add the onion and salt, stir to coat. Cook, stirring every 5 minutes, for 22-25 minutes total until deeply golden, soft, and jammy. Adjust heat if the onion is browning too fast. Do not rush this step.

In a large bowl, combine the all-purpose flour, rye flour, and salt. Add the cold butter and work it in with your fingertips or a pastry cutter until the mixture resembles coarse crumbs with pea-sized pieces of butter still visible.

Press the dough together until it just holds. Divide in half, shape into flat discs, wrap each in plastic, and refrigerate for 15 minutes.

Preheat the oven to 200C. Line two baking sheets with parchment.

On a lightly floured surface, roll one disc of dough very thin, about 2mm. The dough will be rustic and slightly crumbly at the edges — this is correct.

Cut the rolled dough into 8 rectangles (roughly 8x10cm each). Transfer to the prepared baking sheets, spacing 3cm apart. Prick each rectangle all over with a fork.

Bake for 12-15 minutes until the crisps are deeply golden brown at the edges and fully dried out. Remove from the oven and cool on the baking sheet for 5 minutes, then transfer to a wire rack. Repeat with the remaining dough disc.

Spread a generous tablespoon of the mustard butter across each warm rye crisp.

Pile a spoonful of caramelized onion on top of the mustard butter.

Lift 4-5 pickled radish coins from the brine and arrange on top of each crisp. Serve immediately.