Heat butter or oil in a large dutch oven or stock pot over medium until shimmering. Add the onions, leeks, carrots, celery, peppers and mushrooms, stirring to coat in the oil. Saute until the mushrooms have started giving off their liquid, about 10 minutes.

Toss in a pinch of salt and add the potatoes, bok choy, radishes, asparagus, and sugar snap peas to the pot. Stir well and cook until the green vegetables are bright green but still crisp.

Add a bit of the vegetable broth — just to cover the vegetables — and add the fish sauce, bay leaves and thyme. Turn heat to medium-high. Add the remaining broth. When the broth comes to a gentle boil, add the quinoa, reduce heat to medium-low and cover. Simmer for 15 minutes, stirring occasionally.

After 15 minutes, remove the cover and check the quinoa for doneness: the quinoa should be giving off tiny little rings (this is the germ separating from the kernel). No rings? Give it another 5 minutes and check again.

When the quinoa is cooked, reduce heat to low and add the sherry, coconut milk and spinach, and let rest for 5 minutes. Remove the bay leaves. Taste and add more salt, if necessary.

Create a single layer of croutons in the bottom of each bowl. Ladle soup on top, and garnish with cilantro, if using.