Lemon Chicken Salad on Crostini

INGREDIENTS

• 1 French or sourdough baguette, cut into 1/2-inch-thick slices (about 28)
• 2 Tbs. olive oil
• Salt, to taste, plus 3/4 tsp.
• Freshly ground pepper, to taste
• 1 lemon
• 2 skinless, boneless chicken breasts, about 3/4 lb. total, pounded lightly to an even thickness and patted dry with a paper towel
• 1 Tbs. canola oil
• 1/2 fennel bulb, trimmed, quartered lengthwise and finely chopped
• 1 green onion, white and pale green parts only, finely chopped
• 3/4 tsp. finely chopped fresh tarragon, plus more for garnish
• 1/3 cup mayonnaise