Preheat the oven to 400F.
Grate the tofu using a box grater, then toss with olive oil, salt, and pepper.
Spread onto a baking sheet and bake for 20 minutes, until lightly golden and slightly crispy. Let cool.
In a bowl, whisk together yogurt, Dijon, olive oil, poppy seeds, lemon juice, and maple syrup. Season with salt and pepper, and add a tablespoon or two of water to thin, if needed.
In a large bowl, combine baked tofu, celery, apple, walnuts, and red onion.
Pour over the dressing and mix until well coated. Enjoy on its own, in a sandwich, wrap, or over greens.
