Instructions:
To make the salad, at least 4 hours before serving, put the lentils in a large bowl, pour water overtop to cover by about 1 inch, and set aside to soak.
Drain the lentils, place them in a large saucepan, and add the carrots, yellow onion, garlic, bay leaf, thyme, salt, and pepper. Pour in enough water to cover by about 1 inch and bring to a boil over high heat. Reduce the heat to low, and simmer until the lentils are just tender, checking frequently to prevent overcooking, about 10 minutes.
Drain the lentils in a colander, discarding the cooking liquid, bay leaf, and thyme. Pour the lentils and vegetables into a bowl, and set to chill in the refrigerator for about 1 hour.
Heat a small saucepan over medium heat, add the bacon, and sauté until crisp, about 3 minutes. Remove the bacon to drain on paper towels.
To make the dressing, whisk together the chives, red onion, oil, vinegar, mustard, garlic, salt, and pepper in a large bowl.
To assemble the salad, gently toss together the cooled lentils and dressing, and set aside at room temperature for about 30 minutes to allow the flavors to mingle.
In a medium skillet, brown the sausages in the butter over medium heat until cooked through.
To serve, season with additional salt and pepper if necessary. Carefully remove 8 whole leaves of lettuce from the head. Place one lettuce leaf in the center of each plate, then mound one portion of the lentils onto the lettuce. Slice one sausage per plate on a bias and fan over the top of the lentils. Garnish with parsley.