Slice the asparagus into approx. 4 cm lengths then cut into approx. 2 mm thick slices. Combine the stock, vinegar and pepper, mix with the asparagus. Sauté the shallot and morels in oil. Add the vermouth and boil until all the liquid has evaporated. Add the stock and bring to the boil. Reduce the heat, simmer for approx. 5 mins., season.