Wash the sweet potatoes then steam them in a steamer for 30 minutes or until a fork easily pierces the center. Allow them to cool then peel the skins off and put the potato through medium plate of a food mill.
In a suitable pot, combine the pureed potatoes with the milk and coconut milk. Place the pot over medium heat and stir the ingredients together. Adjust the consistency with additional milk. Season to taste with salt and pepper and keep warm until ready to serve.
Check to see that all fat cover and bone fragments are removed from the venison loin. Brush the meat lightly with olive oil. Combine the potato flakes with the black pepper and ginger and roll the meat in this mixture to evenly coat.
Heat a saute pan over medium-high heat and add the olive oil. Sear the venison on all sides until golden brown. Transfer the pan to a 400 degree F. oven and roast until medium rare or to desired doneness, between 5 and 8 minutes.
After cooking the venison, allow it to rest at room temperature for about 5 minutes. Spoon the potato puree into the center of each plate. Slice the venison into 16 slices and place four over each mound of potato puree. Ladle the sauce around the puree and garnish with sprigs of cilantro.