In a large saucepan or Dutch oven, heat the olive oil over medium heat.
Add the chopped onion and celery, cooking for about 5 minutes until they begin to soften.
Stir in the minced garlic and cook for another minute until fragrant.
Add the chopped potatoes, vegetable broth, vegan Worcestershire sauce, salt, and pepper to the pot.
Stir everything together and bring the mixture to a boil.
Once boiling, reduce the heat to low, cover the saucepan, and let it simmer for 15 to 20 minutes, or until the potatoes are fork-tender.
Gently mash some of the potatoes against the side of the pot with the back of a spoon or a potato masher. This helps to naturally thicken the soup while leaving some pleasant texture.
In a separate small bowl, whisk together the soymilk, tofu sour cream, all-purpose flour, and snipped fresh thyme until smooth.
Pour this creamy mixture into the saucepan with the potatoes.
Increase the heat to medium and continue to cook, stirring constantly, until the soup thickens and begins to bubble.
Let it bubble gently for one more minute to cook off the raw flour taste.
Serve hot, garnished with a few fresh thyme sprigs if desired.
