Heat the oven to 425ºF.

• Cut the broccoli into long florets.
• Remove the stem, ribs, and seeds from the red bell pepper; cut the pepper into 1-inch-wide strips.

On one end of a sheet pan, toss the broccoli and bell pepper with 1 to 2 tablespoons oil, season with salt and pepper, and spread in an even layer. On the other end, arrange the sausages and prick them in a few places with a fork. Roast, turning halfway through, until the sausages are browned and cooked through and the vegetables are tender, 12 to 15 minutes.
While the sausages and vegetables roast, prepare the celery root mash.

• Place the celery root on its rounded side; using a sharp knife, trim off the ends. Stand it upright on a cut end and cut away the peel in strips, following the contours of the root. Cut the flesh into quarters, then cut the quarters into ¼-inch-thick slices.
• Peel and thinly slice the shallots.
• Strip the thyme leaves from the stems.

In a medium sauce pot over medium heat, warm 1 tablespoon oil or butter until hot but not smoking. Add the celery root and shallots and cook, stirring often, until the celery root begins to soften, 2 to 3 minutes. Add the vegetable broth and bring to a boil. Reduce to a vigorous simmer and cook until the celery root is tender and only about ½-inch of liquid remains in the pan, 6 to 8 minutes. Stir in the thyme. Using a masher or fork, mash the celery root mixture until smooth. Season to taste with salt and pepper.
While the celery root cooks, finish the sausages and vegetables.

• Strip the parsley leaves from the stems; coarsely chop the leaves.

Remove the sausages, broccoli, and bell pepper from the oven and let cool slightly. Transfer the sausages to a cutting board and cut on the diagonal into ½-inch-thick slices. Return them to the sheet pan with the vegetables and toss with the sherry vinegar, parsley, and as much Urfa biber as you like. Season to taste with salt and pepper.

Transfer the celery root mash to individual plates. Top with the sausages and vegetables and serve.

Chef’s Tip If you prefer a smooth puree to a coarse mash and don’t mind the extra cleanup, in Step 2, puree the parsnip mixture in a blender or food processor.