If you have time, submerge the cut bones in a large bowl of cold, lightly salted water and refrigerate for 12 to 24 hours, changing the water once. This draws out blood and produces a cleaner marrow. Drain and pat the bones completely dry before roasting.

Heat the oven to 220 C / 425 F. Place the bones cut-side up in a single layer on a rimmed sheet pan or in a cast iron skillet. Season the exposed marrow with flaky salt and black pepper.

Roast on the center rack for 15 to 18 minutes, until the marrow is soft, just beginning to bubble at the surface, and pulling slightly away from the bone edges. Check at the 15-minute mark - you want the marrow set but not liquefied.

Remove from the oven and rest for 2 minutes before serving.

While the bones roast, combine the thinly sliced shallot and lemon juice in a small bowl. Let it sit for 5 minutes to soften the raw shallot bite.

Add the parsley leaves, chopped capers, and olive oil. Toss gently to coat. Season with a pinch of salt and black pepper. Do not dress the salad more than 5 minutes before serving.

Brush the sourdough slices on both sides with olive oil. Heat a grill pan over high heat until smoking, then grill the bread for 1 to 2 minutes per side until char marks form and the surface is crisp. Alternatively, use the broiler set to high, placing the bread on the top rack for 2 minutes per side.

Arrange the roasted bone halves on a warm board or plate, cut-side up. Pile the parsley salad alongside. Finish the marrow with a pinch of flaky sea salt at the table. Serve immediately with the grilled sourdough and small marrow spoons or narrow teaspoons for scooping.