Prep the saffron and mise en place. Place the saffron threads in a small bowl with 60 ml warm (not boiling) water and let bloom for 10–15 minutes — this extracts color and fragrance so the saffron perfumes both the braise and the couscous. Rinse and debeard mussels, discarding any that are cracked or do not close when tapped (this ensures safety and quality). Pat shrimp dry and keep refrigerated until use.

Soak and fluff the couscous. Bring 300 ml water to a gentle simmer in a small saucepan with a pinch of salt and half the saffron soaking liquid (reserve the threads and remaining liquid for the braise). Remove from heat, stir in the dry couscous, cover tightly and let sit 6–8 minutes — couscous steams rather than boils, which keeps grains tender and separate. After steaming, fluff with a fork, stir in 1 tbsp chopped parsley and 1 tbsp butter (optional) to finish; the butter adds silkiness and helps the parsley cling to the grains.

Begin the tomato-saffron braise. In a large wide sauté pan or shallow casserole (big enough to hold mussels in a single layer), heat 2 tbsp olive oil over medium heat until shimmering. Add the finely chopped shallots and a pinch of salt and sweat for 3–4 minutes until translucent — sweating (rather than browning) releases sweetness without bitter caramelization that could compete with saffron's floral notes. Add the minced garlic and cook 30–45 seconds until fragrant (garlic browns quickly).

Add tomatoes, preserved lemon (or zest), and the remaining saffron liquid + threads. Stir to combine, then pour in the 200 ml white wine (or stock). Increase heat to bring the mixture to a gentle boil to reduce slightly for 4–5 minutes — this concentrates flavor and cooks off most alcohol while preserving acidity. Taste and season with salt and pepper; preserved lemon is salty, so start light and adjust near the end.

Add mussels and steam. Add the cleaned mussels to the braise, nestling them so they sit in the sauce. Cover the pan and increase heat to medium-high. Steam for 4–6 minutes, checking after 4 minutes: the mussels should pop open as they cook — this indicates they are done and have released flavorful juices into the sauce. Discard any mussels that remain firmly closed.

Add the shrimp last. Remove the lid, give the sauce a quick stir, and add the peeled shrimp in a single layer. Shrimp cook very quickly — usually 2–3 minutes in simmering sauce — until pink and just firm. Stir gently so shrimp cook evenly. Avoid overcooking shrimp, which makes them rubbery; adding them last preserves their texture and sweetness.

Finish the dish. Spoon the mussels and shrimp into bowls over a mound of herbed couscous. Swirl in 1 tbsp olive oil to the braise or a knob of butter if you prefer extra silk, and add the remaining chopped parsley for freshness. Serve with charred lemon halves (see next step) to squeeze over the dish — the quick charring caramelizes the lemon and mellows bitterness while adding smoky depth.

Char the lemons. While the seafood finishes, heat a heavy skillet or grill pan over high heat. Place lemon halves cut-side down and press for 30–60 seconds until dark char marks form and the surface softens slightly. The char concentrates juices and delivers a bright, slightly smoky squeeze that complements saffron and preserved lemon.

Serve and enjoy. Offer extra chopped parsley, flaky salt and freshly ground black pepper at the table. Encourage diners to ladle braise over the couscous so the grains absorb the fragrant sauce, and to squeeze the charred lemon for a final bright note.