In a medium saucepot, add onions, garlic, and thyme. Cook over medium heat, stirring often, until onions turn translucent and just start to brown. About 10 minutes. If the onions and garlic start to stick to the pan, add 2 Tbsp vegetable stock.
Add the crimini mushrooms, sea salt, pepper, and cook until the mushrooms begin to brown, stirring often. This can take 10 minutes.
Add the port and stir for about 1 ½ minutes.
Measure out the vegetable stock. Dissolve the arrowroot into the vegetable stock by whisking it with a small whisk or fork.
Add the vegetable stock and arrowroot mixture to the pan. Add the remaining herbs: parsley, sage, and rosemary.