Lightly oil a 9×13 pan with whatever oil you have on hand. Coconut oil, safflower, sunflower, or vegan butter spread, would work well. Set aside.
Place brown rice cereal and ground flax seed in a large bowl. Stir to combine and set aside.
In a medium-sized sauce pan or frying pan, add rice syrup, sunflower seed butter and vanilla extract. Heat over medium heat, stirring often, until ingredients have liquified, about 5 minutes.
Pour syrup over rice crisp mixture and stir to coat.
Once all crisps have been coated, drop the mixture into the prepared pan and even it out with a spatula, pressing down firmly.
Allow to sit for 1 hour in the refrigerator before cutting into squares.