Preheat the oven to 350°F and lightly oil a six cavity doughnut pan.

In a medium mixing bowl stir together the flour, sugar, baking powder, cinnamon, and salt. In a separate bowl or liquid measuring cup, stir together the milk, coconut oil, and vanilla. Add the milk mixture to the flour mixture and stir just until mixed.

Divide the batter among doughnut cavities.

Bake for 10 minutes, or until the tops spring back when lightly touched. Transfer to a cooling rack to cool.

While the doughnuts bake, combine the coconut sugar, coconut milk, coconut oil, and salt in a small saucepan, then place it over medium heat. Bring everything to a simmer while whisking and lower heat. Allow to simmer for about 5 minutes, whisking constantly, until the mixture darkens a bit and smells like caramel. Watch the pot closely while simmering to avoid burning.

Remove from heat and allow to cool completely. The caramel will thicken as it cools.

When the doughnuts and caramel are cool, dip the top of each doughnut into the caramel to coat it. Place the doughnut on a sheet of parchment paper, and repeat for all of the doughnuts. If you'd like to glaze the bottoms, place the doughnuts into the refrigerator for about an hour to chill, so they're easier to grip without making (as much of) a mess. Sprinkle the tops lightly with coarse ground sea salt and serve.