Place cassava roots into large saucepan or stock pot. Cover with water by 1". Bring to a boil, reduce heat, and simmer 20 minutes. Add 1/4 teaspoon baking soda to water, and simmer an additional 10 minutes. Drain and set aside on cutting board to partially cool.
Preheat oven to 375 degrees Fahrenheit. Grease 2 large cookie sheets. Set aside.
Cut cassava roots into large/long home fries shape. Remove any large inner strings. Dip each cassava fry into melted fat and place on greased cookie sheet in a row. Salt generously, to taste. (See Process Photos below in Recipe Notes.)
Place fries into preheated oven. Bake 35 minutes.
While fries bake, place ground meat, water and apple cider vinegar in a large bowl.
In separate small bowl add dry ingredients: coconut flour, coconut sugar, sea salt, ginger, garlic, onion, rosemary and baking soda. Stir to mix.
Add dry ingredients to wet ingredients. Use handheld electric beaters (or a fork) to mix ingredients together well. Form into 6 to 7 equal size patties on the second greased cookie sheet, each one about 3/4-1" tall and 4-5" in diameter. Set aside until ready to bake. (See Process Photos below in Recipe Notes.)
After fries have baked for 35 minutes (per direction above), remove from oven and flip with an offset metal spatula. Salt again, and return to oven.
At this time, also add cookie sheet of hamburgers into oven.
Bake both fries and burgers 20 minutes. Serve alongside salad.