Step 1

Toast the fennel seeds in a small skillet over medium heat, stirring, until fragrant, about 2 minutes. Pour seeds into a mortar and pound with a pestle until coarsely crushed (or lay seeds on a cutting board and pound them with a can or jar).

Step 2

Put the seeds into a large bowl and stir in lemon juice, zest, garlic, honey, allspice and red-pepper flakes.

Step 3

Season chicken generously all over with salt and pepper and add to the bowl, turning the pieces to coat them with marinade. Mix in plums and thyme sprigs. Refrigerate for at least 2 hours or up to 24 hours.

Step 4

When ready to cook, heat the oven to 425 degrees. Put the chicken pieces, plums, and thyme sprigs on a rimmed baking pan. Add onions, spreading them out around the chicken and plums. Season plums and onions lightly with salt. Drizzle everything with olive oil.

Step 5

Roast until chicken is golden and cooked through, 30 to 45 minutes, removing the white meat if it’s done before the dark meat.

Step 6

Transfer chicken pieces as they are done to a platter. Spoon the plums and onions around the chicken. Drizzle a little of the pan drippings over the chicken and serve, garnished with the herbs and flaky salt.