Preheat oven to 350° F.
Toast nuts and seeds and oats on a rimmed baking sheet until golden brown (~10–12 minutes). Let cool.
Meanwhile, mix egg, butter, sugar, vanilla, salt, and baking soda. Let sit while the nuts are cooling (this will make for a chewier cookie).
Give the batter a good stir, add the flour and combine. Add the dried fruit, chocolate, nuts, and oats and combine until the mix-ins are evenly coated. (It will look like too many mix-ins, but the dough will come together as it chills.)
Cover and chill at least 2 hours and up to 3 days
When ready to bake, heat the oven to 350° F and line two baking sheets with parchment paper.
Using a ⅓-cup measure or #16 cookie scoop, portion out the dough, packing firmly, to make 12 cookies. Using a measuring cup or your hand, press cookies into 2 ½"-diameter disks about ¾" thick; sprinkle with sea salt.
Bake (~11–13 minutes), or until golden brown and no longer wet-looking. Let cool on the baking sheets.