Cream together margarine with sugars until light and creamy. Add vanilla and blend in. In separate bowl mix flour, salt and baking soda. Add to sugar mixture. Stir in water as needed. Add more water if necessary until batter is smooth. Blend in mint extract. Drop spoonfuls of batter on cookie sheet. Bake for ten minutes at 350 degrees. Remove cookie sheet and sprinkle with crushed peppermint candy. Return to oven for 1 minute or until candy begins to melt. Remove and cool on wire rack for twenty minutes. Great with hot cocoa!