In a medium saucepan, combine brown sugar, honey, water, cinnamon, and salt. Bring mixture to a boil stirring frequently. Once mixture reaches a boil, allow to boil for 1 minute whisking constantly.
Remove from heat, stir in vanilla and baking soda and whisk until mixture is foamy. Carefully pour hot sugar mixture over oat mixture and toss to evenly coat.
Spread mixture into an even layer on a silicone baking mat or parchment paper lined 18 by 13-inch rimmed baking sheet.
Bake in preheated oven, about 36 - 40 minutes until lightly golden brown, removing from oven and tossing twice during baking*.
Remove from oven allow to cool completely then break into clusters (note that granola wont be crisp until cooled). Store in an airtight container.