- In a bowl, combine the sliced fennel with the fennel fronds, half of the lemon juice and the salt. Let marinate while you prepare the next steps.
- Meanwhile, in a large non-stick skillet over medium heat, cook the sausages in the oil for 8 to 10 minutes or until cooked through. Pat dry with paper towels. On a work surface, cut each sausage in half lengthwise. Set aside on a plate.
- Meanwhile, in a small bowl, combine the mayonnaise, lemon zest, mint and remaining lemon juice. Lightly season with salt and pepper.
- Spread the lemon mayonnaise over the sliced baguette. Top with the lettuce. Place 4 sausage halves on each piece of bread and garnish with the marinated fennel. Sprinkle with mint leaves, if desired.