Preheat the oven to 325° F and line a large rimmed baking sheet with a silicone mat or parchment paper.
In a small saucepan, combine the brown sugar, honey, oil, and salt. Cook over low heat, stirring frequently, until the mixture is hot and just starts to bubble. Remove from heat.
In a large bowl, combine the oats, almonds, sunflower, and flax seeds. Stir in the sugar mixture to coat.
Spread the mixture onto the prepared baking sheet and bake, stirring every 15 minutes, until the granola is golden (about 45 minutes). Remove the baking sheet from the oven and let cool completely.