It's definitely not a soy aftertaste as I've had tofu which doesn't have the same aftertaste.
Soy has multiple components. Tamari (soy sauce) has the aftertaste I mean, despite not having any artificial additives. Tofu is made from soy milk, which is just one component of soy. You can make your own burgers from very firm tofu, bread crumbs, seasonings, and lightly sauteed onions. Those may also be what you seek, as you can flavor them according to your own taste. My Mom also came up with a very similar recipe for tofu "meat" balls in the Eighties that I adapted a bit and put on the Web years ago. Just search for "Sandy's Italian Tofu Balls."
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