I have not cooked tognue myself but my mom does. She gets a cow from the farm and takes the tognue and seasons it with salt, sugar and msg. Then she puts it in the oven on high or broil. She cooks the cow meat the same way as she cooks the tognue. It is either cooked whole or cut in big chunks to seal in the juice. Once it is cooked it is cut or sliced and then served with a dip usually made from cow bile, cilantro, chives,herbs, soy sauce and peppers.There are many ways Asians bbq, some people marinate their meats oyster sauce, soy sauce, teriyaki sauce, korean bbq sauce, or fish sauce. I'm not sure what kind of bbq your had at that restaurant or how it tasted, but it's all matter of preference. Some people put onions, chives, and garlic, and others keep it simple. If you want to add spice you can put peppers or use sriracha sauce. I have even seen some people use curry. For the most part, at restaurants, they will marinate tognue in some type of sauce or make their own, but when cooked at home, cow tognue is usually just seasoned lightly and baked. The homemade dip made from cow bile, peppers, soy sauce and herbs is also served with tognue along with sticky rice and a side of vegetables(mostly steamed or raw). The dip is bitter because of the bile, but most likely they will not serve that at restaurants because it is very hard to get. Instead they will just skip the bile and just put soy sauce, herbs, and peppers. People usually get cow bile when they go to the farm and get a fresh cow, they ask for the bile. Also, some farmers will not sell the cow bile anymore. Hope this helps.   If you describe the way it tasted I can probably give you a better idea of how it was made.