Preheat the oven to 350 degrees F (175 degrees C).
Spread tofu evenly on a baking sheet.
Bake in the preheated oven until golden, 10 to 15 minutes.
Mix vegan mayonnaise, vinegar, brown rice syrup, and poppy seeds together in a large bowl. Add celery, grapes, green onions, and baked tofu. Mix together and chill in the refrigerator until ready to serve.