What is the foodstuff made from dried soybeans that originated over 2000 years ago?

Tofu is the foodstuff made from dried soybeans that has its origins over 2000 years ago. It is produced by curdling fresh soy milk and pressing the curds into solid blocks. This process allows tofu to retain the protein-rich content of soybeans while giving it a distinctive texture and flavor. Tofu's versatility in cooking makes it a staple in many cuisines, especially Asian, where it serves as a popular plant-based protein source.

In contrast, tempeh, while also made from soybeans, involves fermentation and has a different origin and preparation method. Edamame refers to young soybeans that are typically boiled or steamed and served in their pods, rather than being processed into a food product like tofu. Seitan is made from gluten, the protein in wheat, and is not derived from soybeans, making it a different protein source altogether. Hence, tofu is the correct answer as it specifically represents the dried soybean product that has been utilized for centuries.