1. Preheat oven to 350 degrees F and cover a cookie sheet with parchment paper.
2. In a large bowl, mix together the coconut flour, almond flour, flax seed meal, psyllium husk powder, baking powder, sweetener and salt.
3. Stir in egg whites, oil and apple cider vinegar with an electric mixer.
4. Slowly pour hot water over mixture, stirring until the dough expands.
5. Divide the dough into 6 equal pieces and roll into a ball. Flatten the dough with your hand to 1 inch high. Sprinkle sesame seeds on top of the rolls.
6. Place the rolls on the prepared cookie sheet.
7. Bake 40-50 minutes, until well browned and quite firm to the touch.
8. Remove and let cool on pan.
9. Heat olive oil in a large skillet over medium high heat. Add onions and cook until softened, 2 minutes.
10. Add garlic to the pan and cook for 30 seconds.
11. Add ground beef to the pan and cook until browned and crumbled, 7 minutes.
12. Add in tomato paste, sweetener, mustard, vinegar, broth, salt, pepper and dill pickles. Bring to a simmer and then turn the heat down to low. Simmer for 15 minutes until sauce has been reduced and flavors have melded.
13. Cut buns in half and fill with ground beef mixture. Serve warm.