To prepare vattayappam, wash and soak the rice in water for 3-4 hours.
Drain the soaked rice . Grind to a fine paste with grated coconut.
Add yeast or toddy along with sugar. Keep this bowl covered and in a warm place and let it ferment for 6-8 hours. If you want to prepare vattayappam for breakfast, then you can keep this overnight.
Once the batter has increased in volume, mix in salt, green cardamom powder and keep aside for 30 minutes.
Grease a thali (rimmed dish) or the pressure cooker utensils and pour in the batter, under an inch thickness. Garnish with raisins if using. Steam the vattayappam for 15-20 minutes. Allow to cook for 10-15 minutes and cut into desired shapes.