Mix well the ground lamb with all ingredients under "lamb patty". Make lamb burger patties (about 5-6 patties). Pan fry them until golden brown and cooked through. Set aside.
Paleo burger buns:
Mash the yam using either a fork or a potato masher and season with the ingredients under "paleo burger bun".
Form size golf balls, Use a tarte rim (or egg rim) to press the yam evenly into a tart pan to form a round tarte shape. (Make sure the surface is smooth.)
Heat coconut oil over medium heat, remove the tarte rim and pan-sear the yam until golden brown (around 2 minutes each side)
Assemble the burger:
Layer the burger buns with lamb patties, sliced tomato, and basil.
If you like, insert a toothpick to hold the bun together OR wrap them in wax paper individually.
* Japanese yam has dark red/purple-ish outer skin and white color flesh inside. I found mine at local WholeFoods. Most large Asian grocery stores, Chinese and Korean grocery stores also carry Japanese yams.