For the asparagus panna cotta with tuna tartare, first peel the asparagus for the panna cotta and cut off the woody ends. Cut the green asparagus into thin slices and boil quietly with 200 g whipped cream for 7-8 minutes. Puree with a hand blender and strain through a sieve. Season with cayenne pepper, salt and a few squeezes of lemon juice.
Soak the gelatin according to package directions. Squeeze two sheets of gelatin and dissolve in the hot asparagus cream. Fill four glasses halfway with the green asparagus puree and chill in the refrigerator for 90 minutes.
Also blend the white asparagus, as described above, to a puree and pour on top of the gray panna cotta in the glasses. Chill in the refrigerator for 90 minutes.
For the tartar, cut the tuna into small cubes. Marinate with olive oil and lime juice. Fold in the chive rolls and season with salt and pepper.
Spread the tuna tartar on the panna cotta and serve the asparagus panna cotta with tuna tartar garnished with grissinis.