Make the quick-pickled red onion: Thinly slice about 1/4 small red onion (you’ll only use ~1 tablespoon for the tartine) and place it in a small bowl. Add 1 tbsp white wine or apple cider vinegar, 1 tbsp hot water, 1/4 tsp sugar and 1/8 tsp salt. Stir to dissolve the sugar and salt, press the onion slices down so they’re submerged. Let sit at room temperature for 10 minutes. WHY: Quick pickling softens the raw bite and brightens onion flavor without a long wait; the hot water helps dissolve the sugar and speeds infusion so the onion becomes tender and lively in minutes.

Prep the avocado: In a small bowl, mash 1/2 ripe avocado (about 60 g) with a fork until mostly smooth but still a little textured. Stir in 1 tsp fresh lemon juice and a small pinch of fine salt. WHY: Mashing with a fork keeps texture so the avocado clings to the bread; lemon juice brightens the fat and prevents rapid browning while enhancing the overall lift of the tartine.

Toast the bread: Brush both sides of the 70 g multigrain slice lightly with 1 tsp extra-virgin olive oil or rub with a little butter. Toast in a skillet over medium-high heat for 1–2 minutes per side until golden and crisp, or under a broiler for 1–2 minutes per side. WHY: Toasting creates a sturdy, slightly crunchy base that stands up to the moist avocado and smoked salmon. Brushing with oil encourages even browning and adds a glossy, flavorful finish.

Assemble the tartine foundation: Spread the lemony mashed avocado in an even layer over the warm toast (the toast should still be warm to help release aromas but not so hot that it cooks the avocado). WHY: Warm toast slightly warms the avocado, making it silkier and more aromatic; spreading while slightly warm helps the avocado meld with the bread surface for good adhesion.

Layer the smoked salmon: Arrange 60 g smoked salmon in loose folds over the avocado — don’t press it down. WHY: Folding the salmon creates air pockets and texture, so each bite alternates silky salmon, creamy avocado and crunchy toast rather than a uniform smear.

Top with pickled onion, capers and herbs: Scatter 1 tbsp quick-pickled red onion across the salmon, sprinkle 1/2 tsp drained capers, and add 1 tbsp microgreens or fresh dill. Finish with a small pinch of flaky salt and a crack of fresh black pepper. WHY: The acidic, slightly sweet pickled onion cuts the richness; capers add briny pops and herbs bring freshness. A final sprinkle of flaky salt and pepper sharpens flavors and balances the fatty salmon and avocado.

Final check and serve: Optionally drizzle a few drops of olive oil or a squeeze of lemon if you like extra brightness. Serve immediately so the toast remains crisp. WHY: Serving immediately preserves the textural contrast central to a successful tartine — crisp bread, creamy avocado, tender salmon and crunchy pickles.