Preheat the oven to 325 degrees F. Spread the oats, barley flakes, rye flakes, flaxseed meal, pumpkin seeds, almonds and hazelnuts on a large rimmed baking sheet and bake, stirring once, until lightly golden brown, about 10 minutes. Remove from the oven and let cool.
Add the dried fruit and salt to the mixture on the baking sheet and stir to combine. Transfer to a container with a lid and store in a cool, dry place. The muesli will last for at least a month if stored properly.