if you like indian, try the relatively inexpensive course at the Hare Krishna restaurant in Colegiales!!
I took a short-course at Colegio Gato Dumas (one of the top culinary schools in the city) which was called "Cooking for your friends' but was more like, food you would find in a restaurant but never make at home because it's too complicated. All of the culinary schools have short courses usually 1 month in length. Also there is a school in Soho/Villa Crespo which teaches vegetarian/vegan recipes called "Viento Ligero", also you can take classes with Dan Perlman from Casa Saltshaker; if you want private lessons it's the same cost as one of his regular classes but with a minimum of 2 people required. !!!