How to Make It
In a mortar or spice grinder, coarsely grind the fennel seeds. In a small bowl, whisk the ground fennel with the red wine vinegar and Dijon mustard; season with salt and pepper. Gradually add the olive oil, whisking until the dressing is emulsified. In a bowl, toss the lettuce with the arugula and mint. Add the dressing and season with salt and pepper. Toss well and serve.