Rehydrate the textured soy protein by covering with hot water. Let it sit until tender, then drain and press to remove excess water.

Place the rehydrated soy protein in a mixer with onion, garlic, breadcrumbs, flour, soy sauce, spices, and salt. Blend until you get a homogeneous but not too fine mixture.

If the meatballs are still too moist or crumbly, add a bit more flour, but gradually to avoid making the meatballs too dense.

Form the mixture into meatballs.

Heat a bit of oil in a pan and sauté the meatballs until they are well browned on all sides.

In a saucepan, melt the vegan margarine over medium heat.

Add the flour and stir to create a roux. Continue stirring for about 2 minutes, without letting the flour brown.

Gradually pour in the vegetable broth, constantly stirring to avoid lumps.

Let the sauce thicken slightly, then add the plant-based cream, soy sauce or tamari, and mustard. Stir well to combine all the ingredients.

Season with black pepper to taste and let the sauce simmer for a few minutes to blend the flavors.

Serve the hot sauce with the vegan köttbullar.