Khao soi northern curry
In a medium saucepan, heat 3 tablespoons coconut milk to medium and stir in curry pastes and lime leaves. Stir-fry for about 1 minute, until paste starts to brown and is thick and fragrant. Stir in remaining coconut milk and increase heat to high until boiling. Allow to boil for about 5 to 10 minutes, or until it reduces about a quarter or coats back of a wooden spoon.
Reduce to simmer and add demi-glace, fish sauce, tamarind and sugar. Taste and adjust as necessary. Add beef at last possible moment before serving.
To serve: Separate noodles into 4 bowls. Ladle about 6 to 8 ounces of broth over each noodle bowl. Garnish with mustard greens, shallots, scallions and cilantro.