Line a baking sheet with parchment paper or aluminum foil. Lightly brush each of the baguette slices with the olive oil and place them side by side on the baking sheet (they can be touching, but not overlapping – you may need two baking sheets, or do this in two batches). Sprinkle the bread with coarse salt.
Bake for 4 to 7 minutes until lightly brown. Remember that they will harden as they cool, so take them out before they get too crisp.
In a mixing bowl, combine the lemon juice, olive oil, and honey. Season with salt and pepper and stir in the slivered shallot. Add the onion, chervil, cilantro and parsley to the bowl and toss to coat with the dressing.
In another bowl, combine the creme fraiche, yogurt, cumin, coriander, cayenne, lemon juice and salt and pepper.
Cut the sliced lamb into pieces the right size to put on the crostini, and layer each crostini with some lamb. Place a generous pinch of the herb salad on top of the lamb, then top with a little dollop of the crème fraiche mixture. Serve within an hour.