- 20 1/2-inch-thick diagonal slices crusty baguette
- 20 1/2-inch wedges fresh fennel bulb (from about 2 large bulbs), fronds reserved for garnish
- 20 1/2-inch wedges red onion (from 2 large onions)
- Olive oil
- 3 4 1/2-ounce packages skinless smoked trout fillets, broken into chunks
- On separate baking sheets, arrange bread and vegetables; brush both sides with oil and sprinkle with salt and pepper.
- Prepare barbecue (medium-high heat) or preheat broiler. Grill or broil bread until crisp, about 2 minutes per side if grilled, and 1 to 2 minutes per side if broiled. Grill or broil vegetables until golden and just tender, about 4 minutes per side if grilled, and 3 to 4 minutes per side if broiled. DO AHEAD: Can be made 2 hours ahead. Let stand at room temperature.
- Arrange bread, vegetables, and trout on large platter. Garnish with fennel fronds. Serve, allowing guests to assemble crostini.
- Available at some supermarkets and at specialty foods stores and delicatessens.