Preheat and soak saffron: Preheat your oven to 200°C / 400°F (convection 190°C). Put 2–3 saffron threads into a heatproof spoon or small bowl and pour 1 tbsp hot (not boiling) water over them; let them steep for 5–10 minutes to extract color and aroma. Blooming saffron in hot water releases its volatile oils and gives the quinoa a warm floral tone.

Prepare the roots: Toss the carrot batons, parsnip batons and beet wedges with 1 tbsp extra‑virgin olive oil, a pinch of salt, cracked black pepper and the leaves from the thyme sprig. Spread the roots in a single layer on a rimmed baking sheet - don’t crowd them or they’ll steam instead of caramelize. Roasting at a high temperature concentrates sweetness and develops a caramelized surface.

Roast the roots: Roast the roots in the preheated oven for 22–28 minutes, turning once halfway through, until edges are golden and centers are tender when pierced with a knife. Smaller pieces will cook faster; test at 20 minutes so nothing overcooks.

Warm and season the quinoa: While the roots roast, place 1/2 cup cooked, lightly fluffed quinoa in a small saucepan over low heat. Stir in the saffron water (including the threads) and 1 tsp of the orange zest; heat gently until steaming through. Warming the quinoa with saffron lets the grain absorb the color and perfume without losing texture.

Make the orange‑caper vinaigrette: In a small bowl whisk together 1 tbsp orange juice, 1 tsp Dijon mustard, 1 tbsp drained capers (roughly chopped if the capers are large), the minced shallot and garlic, 1 tbsp extra‑virgin olive oil (from the roots; or reserve a small splash), a pinch of salt and cracked black pepper. Taste and balance: more mustard for bite, more orange juice for brightness. The acid + caper brine is what brightens the whole plate.

Pat and season the fish: Pat the sea bass fillet very dry with paper towels (moisture prevents a good sear). Season both sides with salt and cracked black pepper and gently score the skin if it’s on — this prevents the fillet from curling when cooking.

Pan‑sear the sea bass: Heat a heavy skillet (cast‑iron or stainless steel) over medium‑high heat until hot. Add 1 tsp olive oil and swirl to coat. Place the fish skin‑side down (if skin on). Press gently with a spatula for 10–15 seconds to ensure even contact — this helps the skin render and crisp. Cook undisturbed until the skin is deeply golden and crisp, about 3–4 minutes depending on thickness.

Finish the fillet: Flip the fish, add 1 tsp butter to the pan and baste (spoon the foaming butter over the top) while cooking the second side for 1–2 minutes until the internal temperature reaches about 52–55°C (125–131°F) for moist, just‑cooked fish. Rest for 2 minutes — residual heat will carry the fish to a perfect doneness while juices redistribute.

Combine quinoa and vinaigrette: Fold 1–2 teaspoons of the orange‑caper vinaigrette into the warm saffron quinoa (reserve the rest for drizzling). The vinaigrette adds acidity and a silky mouthfeel to each spoonful of quinoa.

Plate: Spoon the saffron quinoa onto the center of a warm plate, arrange roasted roots to one side, and place the sea bass on top or beside the quinoa. Scatter baby arugula around the plate for peppery freshness. Drizzle remaining orange‑caper vinaigrette over the fish and roots, and finish with a few whole capers, a little extra orange zest and a grind of black pepper.

Final checks: Taste a root and the quinoa to check seasoning; add a final pinch of flaky salt if desired. Serve immediately so the fish remains crisp and the quinoa warm.