Heat your grill to high (the oven would work if you don’t have a grill) Rub the tempeh block with oil, a pinch of salt and pepper, and about 2 Tbsp of the buffalo sauce. Let sit for 5-10 minutes while the grill gets hot. In the meantime chop the onion, celery, and cilantro and mix in a bowl with the soy yogurt. Add salt if desired. Grill the tempeh block for 2 minutes or so on each side, until heated and just marked by the grill.