How to Make It
Bring a large saucepan filled with water to a boil over high. Gently lower eggs into water; boil 8 minutes. Remove eggs from water, and plunge into a bowl filled with ice water; let stand 5 minutes. Drain and peel eggs. Slice lengthwise into thirds; season with salt and pepper to taste. Set aside.
Whisk together olive oil, rice bran oil, rice vinegar, thyme, shallot, and sugar in a small bowl until well combined. Season with salt and pepper to taste; set aside.
Layer tuna, boquerones, sun-dried tomatoes, eggs, and arugula on bottom baguette half. Spoon vinaigrette over cut side of top baguette half; place top baguette half on sandwich.
Cut sandwich in half crosswise; arrange halves side by side on a baking sheet. Place a second baking sheet on top of sandwiches; weight with a cast-iron skillet or several canned goods. Let stand at room temperature 2 hours. Cut each sandwich in half, and serve.