Drain the tofu and wrap in a towel, press lightly to extract water, then cube and reserve.
In a large saute pan, heat the coconut cream over medium-high heat and add the turmeric and curry paste. Stir until it comes to a boil. Add the salt and lime zest and stir in the vegetable stock. Bring to a simmer. Lower the heat and cook for at least five minutes, adding water or more stock if it gets too thick.
Add the sweet potato and jalapeno and stir, when it boils, reduce to a simmer and cover. Cook for about 8 minutes, until the sweet potato cubes are tender when pierced with a knife. Fold in the tofu and simmer gently until thick.
In another pan, heat the oil over high heat and sear the mushrooms. Cook, stirring, until browned and shrunken. Keep warm.
Cook the noodles according to package directions. Serve curry topped with shiitakes, cilantro and scallions.