Combine water, soy sauce and cornstarch in a small bowl
Dry saute mushrooms, onion and garlic in sauce pan over medium heat. Cook down until water has released and just evaporated from mushrooms, stirring frequency, ~5-7 minutes
Add dried thyme and cook for ~30 second more to coat vegetables
On high heat, add liquid mixture slowly, stirring constantly
Continuing stirring constantly and wait for gravy to darken and thicken, until it has come back up to a boil
Remove from heat and serve over mashed potatoes or alongside your favorite recipe
Enjoy!