Bring water with lemon juice to a boil in a saucepan.
Remove the sand from the salsify under running water with a brush, then peel with a peeler, cut diagonally into 2 - 3 cm long pieces and cook in simmering lemon water for approx. 20 minutes. Strain and evaporate briefly.
Melt the butter in a pan, add breadcrumbs, spices and black salsify and brown very lightly by swirling several times. Season to taste with salt.