I followed the recipe to the letter. The curry came out too spicy and was overwhelmed with mustard flavor. It should perhaps be read as 1/2 teaspoon mustard.
From EatingWell: September/October 1993
Serve with the Indian flatbreads known as chapatis for a vegetarian meal or use as an accompaniment for simple grilled fish or chicken. If you'd like a hotter taste, do not remove seeds from the jalapeño pepper.