Tomado de http://japanesefood.about.com/od/curry/r/curryroux.htm
Ingredients:
2 Tbsp butter
1 onion, thinly sliced
1 tsp grated fresh ginger
1 tsp grated garlic
2 Tbsp flour
1 Tbsp curry powder
2 and 1/2 cup bouillon
1/2 tsp garam masala
Preparation:
Heat 1 Tbsp of butter in a skillet and saute onion slices on low heat until they are brown. Add garlic and ginger and saute well. Set aside. Heat 1 Tbsp of butter in a medium pot. Put flour and saute on low heat. Add curry powder and mix well. Add bouillon little by little, stirring well. Add onion in the sauce. Simmer the sauce until thickened. Add garam masala at last.