Preheat oven to 350°F (176°C).
Blitz: Add ½ cup of the oats to a blender or food processor and blitz into a flour.
Wets: Stir oat flour together with ¼ cup vegetable oil, ¼ cup honey, and 1 tsp vanilla extract.
Dries: Stir in remaining rolled oats, ¼ cup brown sugar, ¼ tsp baking soda, and ¼ tsp salt.
Press: Line a baking dish (7x9 inch or similar) with parchment paper, then transfer oat mixture into it. Press the mixture firmly down into the pan (use the bottom of a glass to flatten it).
Bake for 20 to 25 minutes or until golden brown and firm. Immediately after taking it out of the oven, use the bottom of a glass to press the bars, flattening the top firmly. Let cool fully before cutting into bars.
