Have the meat stock, cooked chopped chicken or turkey, and 8 ounces cooked spaghetti-squash strands ready.
Heat the fat in an extra-large stainless pot over medium-high. Add the onion, green-onion whites, and 1/2 teaspoon sea salt. If using celery instead of mushrooms, add it now.
Cook for 15 minutes, stirring occasionally and lowering the heat after 5 to 10 minutes so the vegetables soften without getting too dark. For the mushroom branch, add the sliced mushrooms after 10 minutes.
Stir in the onion powder, garlic powder, ginger or pepper, and dried thyme. Cook 2 minutes until fragrant, then stir in the fresh garlic.
Whisk the homemade coconut milk and additive-free homemade mustard together in a large glass measuring cup. Do not add tapioca or another starch.
Add 2 cups chicken meat stock to the vegetables and bring to a gentle simmer over medium heat.
Whisk the coconut-milk mixture again and pour it in. Stir through the vegetables, add another 2 cups stock, and return to a gentle simmer.
Hold the optional fifth cup of stock to adjust the finished consistency rather than adding it automatically.
Add the chicken or turkey, spaghetti squash, green-onion greens, and lemon juice. Stir gently until everything is very hot, keeping the squash strands intact. Taste and add the remaining salt as needed.
Stir in most of the fresh thyme. Ladle into bowls and finish with the remaining thyme.