Bring the ricotta to room temperature (15–20 minutes). Softer, room-temperature ricotta spreads more smoothly and carries the lemon and olive oil flavors better than cold ricotta straight from the fridge.

Segment the blood oranges (supreme them): using a sharp knife, cut off both ends, then slice away the peel and white pith, following the curve of the fruit. Working over a bowl to catch juice, cut between the membranes to release clean segments. Reserve any squeezed juice for the fennel dressing. Doing this gives you pretty, membrane-free segments that melt on the tongue and release bright citrus flavor without bitterness.

Very thinly shave the fennel bulb: trim the stalks and fronds (reserve a little frond for garnish), then use a mandoline set to a thin setting or a sharp chef’s knife to slice the bulb as thin as you can (30 g per person / 120 g total). Thin slices are key — they give crisp, anise-like crunch without overtaking the delicate trout.

Make a quick fennel dressing: whisk together the reserved blood orange juice (about 1–2 tablespoons), 1 teaspoon olive oil, a pinch of salt and a few grinds of black pepper. Toss the shaved fennel with this dressing and let it sit 5–10 minutes to soften very slightly and absorb citrus — this brightens the fennel and ties it to the orange flavor in the dish.

Season and fold the ricotta: in a bowl, mix the room-temperature ricotta with the lemon zest (1 teaspoon total), a pinch of salt, 1 teaspoon of olive oil, and a few grinds of black pepper. Taste and adjust salt — ricotta benefits from seasoning to avoid tasting flat. The lemon zest brings aromatic lift without additional acidity so the ricotta remains silky.

Toast the sourdough slices until golden and crisp (either under a broiler for 1–2 minutes per side, in a 200°C/400°F oven for 5–7 minutes, or in a hot skillet with 1 tsp butter or oil). Toasting is essential: a sturdy, crisp base keeps the toppings from making the bread soggy and gives a pleasant contrast of texture.

Assembly — first layer: liberally smear about 40 g (roughly 2 generous tablespoons) of the lemon ricotta onto each warm slice of toast. Spreading on warm toast helps the ricotta relax and coat the bread evenly.

Second layer: arrange a small handful of the dressed, shaved fennel over the ricotta. The dressed fennel adds crunch and an herby, citrused backbone that lifts the smoky fish.

Add the trout and oranges: gently flake 50 g smoked trout per toast and distribute it in small, delicate pieces so it sits evenly; top with 2–3 blood orange segments per slice. Flaking the trout into bite-size pieces makes each mouthful balanced — you want bits of smoke with each citrus pop.

Finish and season: drizzle each bruschetta with the remaining olive oil (about 1 teaspoon per slice), scatter 1 tablespoon chopped fresh dill per slice (or divide evenly), and finish with a light grating of lemon zest, a few cracks of black pepper and a pinch of flaky sea salt if you have it. A finishing salt and fresh dill brighten the flavors and add a professional-looking finish.

Serve immediately: serve the bruschetta right away while the toast is still crisp. If you assemble too far in advance the bread will soften; keeping components separate until the last minute preserves the textural contrast.