Preheat oven to 200C. Place ficelle slices in a single layer on an oven tray. Drizzle with 20ml olive oil, season to taste and bake until golden and crisp (5-8 minutes), set aside to cool.
Meanwhile, for white onion and anchovy paste, heat olive oil in a saucepan over medium heat, add remaining ingredients, stir occasionally until onion is very tender (10-15 minutes). Remove thyme, season to taste, process in a food processor until very smooth, set aside.
Heat 20ml olive oil in an ovenproof frying pan over medium-high heat. Season veal to taste. Add to pan and turn occasionally until browned on all sides (5-6 minutes) then transfer to oven and roast until medium-rare (2-3 minutes). Rest for 10 minutes covered wtih foil, then slice very thinly.
Combine herbs, anchovy, lemon rind, lemon juice and remaining oil in a small bowl, season to taste.
To serve, spread crostini with onion and anchovy paste, top with sliced veal, spoon over herb oil and serve immediately.
Note Ficelle is a thin breadstick available
from select bakers. If unavailable, substitute a baguette.