Step 1: Preheat the Oven and Prepare the Baguette

Start by preheating your oven to 400 degrees Fahrenheit. This temperature ensures the baguette toasts evenly without becoming overly hard. Take half of a crusty baguette and slice it down the center lengthwise to create two open halves.

This split allows for even toasting and maximum topping coverage later. Place the baguette halves cut-side up on a baking sheet. Drizzle each half lightly with extra virgin olive oil, focusing on the cut surfaces to enhance crispiness and flavor absorption. The oil prevents drying and adds a subtle richness that complements the tuna. Slide the baking sheet into the preheated oven.

Bake for about 10 minutes, checking midway to avoid over-toasting. You want a light golden color and a firm, crunchy texture, not a rock-hard crust. The toasting step is crucial as it provides structure to hold the moist tuna mixture without sogginess.

While the baguette toasts, move on to preparing the tuna salad. This parallel timing keeps the process efficient, totaling around 15 minutes of active prep. Remove the baguette from the oven and let it cool for 5 minutes on the baking sheet. Cooling allows steam to escape, maintaining crunchiness. Handle carefully to avoid burns, as the sheet retains heat.

Step 2: Drain and Flake the Tuna

Open a 6oz can of Italian tuna packed in olive oil. High-quality Italian brands ensure superior flavor and texture, with firm flakes that hold up in the salad. Drain the olive oil from the can into a small bowl or discard it; reserve if you want extra for drizzling later.

Empty the tuna into a mixing bowl. Use a fork to gently flake it into smaller pieces, breaking up any large chunks. This even flaking distributes flavor uniformly throughout the sandwich. Avoid over-mashing to preserve some texture contrast with the crisp baguette and arugula.

Inspect the tuna for any bones or skin, removing them if present, though premium cans are usually clean. The natural oils from the tuna will still provide moisture to the mixture. Set the bowl aside momentarily while gathering other ingredients. This step takes under 2 minutes but sets the base for the entire filling.

Step 3: Chop Vegetables and Herbs

Finely chop ¼ cup of red onion. Small dice ensures bursts of sharp, sweet flavor in every bite without overpowering raw onion bite. Rinse and pat dry ¼ cup of Kalamata olives, then chop them roughly to release their briny juices. Chop 2 tablespoons of fresh parsley finely; its bright green flecks add color and herbaceous freshness that balances the richness. Rinse 2 tablespoons of capers briefly if salty, then chop lightly to integrate their tangy pop.

Measure 2 cups of fresh baby arugula and set aside; no chopping needed as its tender leaves provide peppery crunch. These Mediterranean staples create layers of flavor: onion for bite, olives and capers for saltiness, parsley for earthiness. Chopping uniformly, about 1/8-inch pieces, aids even mixing. This prep builds anticipation as aromas mingle. Total chopping time is 5 minutes.

Step 4: Mix the Tuna Salad

Add the chopped red onion, Kalamata olives, parsley, and capers to the bowl with flaked tuna. Squeeze the juice of one lemon (or half if less tartness preferred) over the mixture. Start with half and taste; lemons vary in juiciness and acidity. The lemon brightens everything, cutting through tuna’s richness and enhancing olive oil notes. Drizzle in 2 tablespoons of extra virgin olive oil for silkiness and to bind ingredients.

Season lightly with salt and pepper. Go easy on salt due to briny olives and capers; taste and adjust. Use a fork or spoon to toss gently until combined. Let the salad sit for 5-10 minutes at room temperature. This resting allows flavors to meld: lemon tenderizes onion slightly, olives infuse tuna. Stir once more before assembly for even distribution. The result is a vibrant, no-mayo tuna salad superior in freshness.

Step 5: Assemble the Base

By now, the baguette has cooled sufficiently. Identify the bottom half (slightly denser side) for stability. Drizzle a touch more extra virgin olive oil over the toasted cut surfaces. This keeps the bread moist and ties flavors. Spoon the tuna mixture generously over the bottom half, spreading evenly with the back of the spoon. Pile it high for a substantial sandwich; the volume fits perfectly on half baguette.

Add a handful of baby arugula over the tuna. Press lightly to nestle leaves in; they wilt slightly from moisture, adding peppery contrast without sogginess. Scatter a few extra arugula leaves for garnish and crunch. Avoid overpacking to prevent spillage.

Step 6: Complete and Cut the Sandwich

Place the top baguette half over the fillings, pressing gently to secure. For serving two, slice the full sandwich in half crosswise with a serrated knife for clean cuts through crust. For smaller portions or appetizers, cut into quarters. Each piece showcases layers: golden toast, vibrant green arugula peeking out, tuna glistening. Drizzle any remaining lemon juice or olive oil over top if desired for shine.

Serve immediately for peak crunch, or wrap individually for lunch. Keeps tuna and bread separate if prepping ahead to avoid sogginess. Cutting exposes fillings enticingly, making it shareable. Total assembly under 5 minutes.