In a small bowl combine 1/2 cup mayonnaise, 1 tsp lemon zest, 1/2 tsp Dijon, 1 tsp minced capers, 1 tsp hot sauce (optional) and 1/4 tsp salt. Whisk until smooth, taste and adjust seasoning. Refrigerate until ready to serve.

Prepare Toasts

Preheat oven to 375°F (190°C). Arrange baguette slices on a baking sheet. Lightly brush each slice with melted butter or olive oil. Toast in the oven 6–8 minutes, turning once, until edges are golden and crisp. Remove and let cool slightly.

Make Tuna Tartare

Pat the sushi-grade tuna dry with paper towels and trim any sinew. Finely dice into uniform small cubes (~1/4" dice) and place into a chilled bowl.

Add 2 tbsp minced red onion, 2 tbsp chopped capers, and the finely diced 3 cornichons to the tuna. Add 2 tbsp snipped chives.

In a small bowl whisk together 1 tbsp extra-virgin olive oil, 1 tsp fresh lemon juice, 1 tsp Dijon mustard, 1 tsp sea salt and 1/2 tsp freshly ground black pepper. Taste and adjust: add a little more lemon or olive oil if needed. Pour this dressing over the tuna mixture and gently fold until evenly coated. Chill for 10–15 minutes to allow flavors to marry, but do not let sit so long that the tuna becomes overly cold or water-logged.

Taste and correct seasoning just before plating: add more salt, pepper or a squeeze of lemon as desired.

Assemble & Serve

Spread a thin layer (about 1–1.5 tsp) of the house mayonnaise onto each toasted baguette slice.

Use a small ring mold (1.5–2" diameter) or a spoon to portion tuna tartare (about 2 oz / 55 g) onto each toast. Press lightly so it sits neatly on the mayo layer.

Garnish each tartare with a few microgreens or extra snipped chives and, if desired, a tiny sprinkle of minced caper. Serve immediately with lemon wedges on the side.