Rinse and soak the Parboiled Rice in enough Water to cover for at least 4 hours or overnight; drain well before using.
In a blender or wet grinder, combine the soaked rice with the Cooked Rice and some water; grind to a smooth, slightly grainy batter, adding water as needed so the texture is pourable but not watery.
Warm a small amount of water until lukewarm, then dissolve the Sugar and sprinkle in the Active Dry Yeast; let sit 5–10 minutes until foamy, then stir this into the rice batter.
Season the batter with a pinch of Salt, mix thoroughly, cover, and keep in a warm place to ferment until it becomes bubbly and slightly increased in volume (about 6–10 hours or overnight).
After fermentation, gently stir the batter and fold in most of the Thick Coconut Milk, reserving a little for serving; the final consistency should be thinner at the edges and a bit thicker in the center when ladled.
Heat an appam pan or a small nonstick/skillet over medium-high heat and brush the surface with Coconut Oil.
Pour a ladleful of batter into the center of the hot pan, immediately swirl or tilt the pan to coax thin, lacy edges while keeping a thicker center; reduce heat to medium-low, cover, and cook until the edges are crisp and the center is set (do not flip).
If you like a creamier center, spoon a little of the reserved Thick Coconut Milk into the middle of the appam before covering to finish cooking.
Remove the appam gently with a spatula, brush with a touch more Coconut Oil if desired, and repeat with the remaining batter. Serve hot with stew, curry, or sweetened coconut milk.
