Yam: Wash the yam, place it in a saucepan, cover with water and place the pan on a medium to high heat. Bring the water to a boil, cover the saucepan and allow the yam to continue a gentle boil for about 20 to 30 minutes. The yam is done when you can pierce it easily with a knife. Mash the yam with a fork.
Wild rice: Place 1/3 cup wild rice, into 1 cup water in a saucepan with a lid over medium-high heat.
Put the lid on and bring it to a boil. Turn the heat down to low and let it simmer for 40-45 minutes. You will know that it is cooked when some of the kernels are burst open.
Drain excess liquid.
Preheat the oven to 400 degrees Fahrenheit.
Line a sturdy baking sheet with parchment.
Mix the water and flaxseed meal together in a small bowl, set aside for at least 10 minutes (this makes 2 flax eggs). It will gel up.
Wash and scrub the kabocha squash well under running water.
Using a strong knife, cute the cap off of the squash (like a Jack-o-Lantern).
Clean the kabocha squash of seeds and string.
Place the mashed yam, cook wild rice, flax egg, diced celery, minced garlic, goji berries, herbs, salt and pepper in a large bowl and mix it all together.
Stuff the kabocha squash with the mixture, being careful not to overstuff. (You may have some stuffing left over.) Top stuffed squash with the cap.
Transfer squash to the parchment-lined baking sheet and cook for 46-60 min. Remove the cap and continue to cook for an additional 15-30 minutes, until the flesh of the kabocha squash is soft and easily pierced with the tip of a knife.
To serve, either slice wedges from the squash like a pie or scoop out servings, being careful to scoop out the kabocha fresh with the stuffing.