TIP: Thirty minutes before serving, slice the radishes, and and place them in ice water. They become really crispy and mild.
To make crostini, brush sixteen 1/4-inch-thick slices of baguette on both sides with 3 tablespoons olive oil and sprinkle with 1/2 teaspoon salt. Place on a baking sheet and bake in a 400-degree oven for 10 minutes, rotating halfway through.
Mix together creme fraiche, basil, chives, tarragon, olive oil, lemon zest, lemon juice and salt in a medium bowl. Add the crabmeat and gently fold it into the herb dressing until the crab is coated and the herbs are evenly distributed.
In a separate bowl, smash the avocado and add a sprinkle of salt and another squeeze of the lemon. Mix well.
Top each crostini with a teaspoon of smashed avocado, a few slices of radish and a tablespoon of the crab mixture.
The salad for your crab crostini can be made up to 1 day ahead and stored, tightly covered, in the refrigerator.