Sprinkle the sugar over the prepared tart tin.
Caramelize for approx. 4 mins. in the centre of an oven preheated to 220 °C until the sugar turns a light brown colour, remove.
Blanch the asparagus in boiling salted water for approx. 2 mins., dip briefly in ice-cold water, drain.
Spread the butter and shallots on top of the caramel. Add the asparagus, drizzle with oil. Prick the pastry firmly with a fork, place loosely over the asparagus, make a rim between the asparagus and the edge of the tin.
Approx. 25 mins. in the centre of an oven preheated to 220°C. Remove the tart, leave to stand for approx. 2 mins., turn out onto a plate.