Pre-heat oven to 350F and line a baking sheet with parchment paper.
Put the flaxseeds in the food processor and grind for a minute or two until most are broken up but still have some whole pieces.
Add hot (you can use boiling water, just let it cool for a few minutes) to the blender and pulse until the mixture it just combined. Let it sit for 3 minutes to thicken.
Add the vinegar, baking soda, salt, lemon juice, lemon zest, and pulse a few more times. Add in the coconut flour, rosemary and other herbs and pulse until the dough comes together and forms a ball.
Using oiled hands, mix the dough and pat flat on the baking sheet - about 1/4 inch thick. Use your fingers to poke dimples into the dough. Add in the sliced tomatoes, (or the halved cherry tomatoes, sun-dried tomatoes or kalamata olives) and press into the dough. If using sliced tomatoes, just remove some of the juice in the tomato so the dough doesn't get soggy.
Sprinkle the minced onion, garlic powder and any other herbs - like extra rosemary on top.
Bake for 30 minutes, then turn the oven up to 400 and bake for another 7 minutes until the edges are light brown and crispy.
Eat and enjoy!