Kohlrabi Caesar Salad

Ingredients
Method
Gently toss smoked trout, lemon zest, red pepper flakes, 1/4 cup mixed herbs, and 1/4 cup olive oil in a large bowl to combine; season with salt and black pepper. Let sit at room temperature 20 minutes.
Meanwhile, preheat oven to 350°F. Drizzle both sides of bread with olive oil; season with salt. Toast on a rimmed baking sheet until golden brown and crisp, 8–10 minutes. Let cool, then crumble into small pieces. Set croutons aside.
Whisk egg yolk, garlic, and 1 tsp. lemon juice in a medium bowl to combine. Whisking constantly, gradually add vegetable oil and 2 Tbsp. olive oil, drop by drop at first, then in a steady drizzle; whisk until aioli is thickened and emulsified. Stir in 1 tsp. water to loosen sauce; season with salt.
Add kohlrabies and remaining 1 Tbsp. lemon juice to bowl with smoked trout mixture. Season with salt and pepper, drizzle with olive oil, and gently toss to combine.
Spread aioli on a large plate and top with kohlrabi salad, shaved Parmesan, reserved croutons, and remaining 1/4 cup mixed herbs.
Aioli can be made and trout marinated 1 day ahead. Cover and chill separately.