Preheat oven to 350 degrees F and line two baking sheets with parchment paper or a Silpat. Set aside.
Whisk dry ingredients together until no clumps remain, and set aside.
In the bowl of an electric mixer fitted with the paddle attachment, or in a a large bowl with a handheld mixer, beat palm oil on medium until soft and fluffy, 1-2 minutes. Scrape down the sides of the bowl.
Add tahini and beat on medium again until combined and smooth, about another minute. Scrape down the sides of the bowl. Add honey, coconut sugar, and vanilla, and beat again until combined and smooth. Add flax egg and beat on medium until just combined, about 30 seconds.
Lastly, add dry ingredients and beat on medium-low until just combined. Dough will be thick, firm and sticky. Add chocolate chips and chunks and stir by hand to combine.
Form dough into 12 equal sized balls, and place on baking sheets a couple of inches apart. Sprinkle a small pinch of flaky sea salt on the top of each cookie.
Bake one tray at a time, in the center of the oven. Bake for 5 minutes, then turn tray 180 degrees, and bake for another 5 minutes. Cookies should be golden on the outer edges, and slightly dry and cracked on top. Repeat and bake the second tray.
Set trays on racks until cool enough to handle, then transfer direct to the rack to finish cooling completely. It will be very tempting to enjoy a cookie right when they come out of the oven. Note they will crumble or break into pieces when hot, but hold together once cooled, even partially.
Store in an airtight container in the refrigerator for one week, or up to a month in the freezer.