In a saucepan, heat the oil.
Add the ginger, garlic and serrano pepper.
Saute until the ginger and garlic brown.
Add the garam masala and paprika and stir.
Add the tomato sauce and water.
Bring to a boil; reduce the heat and simmer until thickened, about 15 minutes.
In another pan, heat 1 or 2 more tablespoons of oil.
Add the cumin seeds and toast for about 10 seconds.
Stir in the onions and bell pepper. Saute until softened and starting to brown.
Add the serrano pepper. Saute for a couple of minutes, seasoning with a bit of salt.
Stir in the turkey. Cook until opaque, about 5 minutes.
Pour the sauce into the skillet with the turkey. Stir and boil; then, lower the heat and simmer until the mixture has thickened slightly, about 10 minutes.
Remove the serrano pepper once the turkey is cooked and the sauce has thickened.
Add the honey and half-and-half.
Stir and taste for seasoning.
Stir in fresh cilantro before serving.
Toast the buns, fill them with the turkey mixture, and serve.