Line an 8 x 8-inch or 9 x 9-inch baking pan or glass baking dish with parchment paper. In a large bowl, mix the oats, cereal, salt and raisins. Set aside.
In a small pot, melt the butter, syrup and brown sugar. When it starts to boil, reduce the heat to medium-low, and cook for 4 minutes, making sure the mixture continues to minimally bubble while siring often. Turn off the heat and add the vanilla.
Pour the liquid mixture into the dry ingredients, and mix well to combine all ingredients. Place the mixture into the baking dish. Cover with parchment paper, and press down with your hands until the mix is well packed. (Just when you think you've pressed down enough- press some more!)
Allow the pan to cool at room temperature for at least 2 hours. Lift parchment paper out onto a cutting board and slice into 12 bars. After cutting the bars, store in an airtight container or ziplock bag for up to 1 week.
You can find brown rice syrup in the baking aisle of your health-food store and online. Alternatively, you could use honey, but the bars will be sticky and they tend to break apart easier, which is why Laura doesn't recommend using it.