Soupe de Poisson avec Rouille and Braised Leeks

Dice the onion, slice the fennel bulb thinly, mince the garlic, and zest the orange for the soup; trim the leeks by removing tough green tops and root ends, then halve lengthwise and rinse thoroughly to remove grit for the side dish.

Heat olive oil in a large pot over medium heat (about 160°C); sauté the onion and fennel for 6–8 minutes until softened and translucent; add garlic and cook for 1 minute until fragrant; stir in crushed tomatoes, saffron, and orange zest, cooking for 2 minutes to meld flavors.

In a wide skillet, heat olive oil over medium heat (about 160°C); arrange leeks cut-side down in a single layer and cook for 3 minutes until lightly golden; pour in vegetable broth, season with salt and pepper, cover, and reduce heat to low (about 120°C), simmering for 20 minutes until tender.

Pour the broth into the pot with the soup base, bring to a boil over medium-high heat (about 200°C), then reduce to a gentle simmer (about 90°C) and cook uncovered for 20 minutes; season with salt, pepper, and cayenne, adjusting to taste.

Steep saffron in hot water for 5 minutes; in a blender or with a whisk, combine egg yolks, garlic, saffron water, and lemon juice; slowly drizzle in olive oil in a thin, steady stream while blending to form a thick, golden mayonnaise; season with salt and cayenne.

Add cubed fish to the simmering soup and cook for 4 minutes at a gentle simmer (about 85°C); add prawns and cook for an additional 3 minutes until pink and just curled, ensuring not to boil vigorously to avoid toughening the seafood.

Check leeks for tenderness with a fork — they should be soft but hold shape; if done, remove lid and let any remaining liquid reduce for 1–2 minutes over medium heat (about 160°C) for a slightly caramelized finish.