Time: 45 minutes, plus freezing time

8 tablespoons unsalted butter

1 tablespoon plus 1 teaspoon caraway seeds

1 large red onion, peeled, halved through the root and thinly sliced crosswise

1 tablespoon extra virgin olive oil

Fine sea salt

130 grams rye flour (about 1 cup)

130 grams all-purpose flour (about 1 cup)

1 teaspoon baking powder

1/4 teaspoon baking soda

1/2 cup sour cream plus more for brushing

1 large egg

1 teaspoon honey

1/3 cup dried currants or chopped raisins

Demerara (raw) or granulated sugar, for sprinkling

Flaky sea salt, like fleur de sel or Maldon, for sprinkling (optional).