Preheat oven to 350 degrees. Butter & flour a Bundt pan or a large loaf pan.
In small saucepan, add raisins and water. Bring to boil and simmer 1-2 minutes, then remove from heat and add baking soda. Cool to room temperature (about 20 minutes).
In a large bowl, sift flour and sugar.
If using nuts, add them to a small bowl and sprinkle a little of the flour mixture into them (this will prevent them from sinking to the bottom of the batter while cooking); set aside.
To the bowl of flour/sugar, add beaten eggs, oil and vanilla and mix well with a wooden spoon. Add raisins and water; stir to combine. Toss in nuts (if using) and stir to combine.
Transfer batter to prepared baking pan. Bake about 1 hour, until a toothpick comes out clean at the center. Remove from oven, cool thoroughly, then transfer to a serving platter.