Preheat oven to 250 degrees F (120 degrees C). Line a baking sheet with parchment paper.
Stir rolled oats, wheat bran, oat bran, and flax seed meal in a large bowl until well blended.
Combine honey and oil in a saucepan; cook and stir over medium-low heat until mixture starts to boil, about 3 minutes. Lower heat to low and simmer for another 2 minutes.
Remove saucepan from heat and stir in chocolate chips, vanilla extract, and salt. Pour chocolate mixture over dry oat mixture and stir until well coated; spread evenly over prepared baking sheet, gently pressing mixture down with spatula.
Bake in preheated oven for 30 minutes. Rotate baking sheet adn continue baking until slightly crisp, about 30 minutes more. Remove baking sheet from oven and cool granola until crisp, about 15 minutes. Break into chunks and store in an airtight container.
