Place soy protein in a pot and cover with water. Bring to a boil and boil for 3 minutes. Drain and rinse very well with clean water. Allow to cool completely, about 30 minutes.

Place hydrated soy in a glass bowl and pour lime juice over it. Let stand for 30 minutes. Drain lime juice. Mix in tomatoes, cucumbers, onion, cilantro, and jalapeno. Season with oregano and salt. Serve over tostadas and garnish with avocado.