Buddhist temple cooking leaves out meat and fish. It's often the easiest fully plant-based meal in Japan. The stock is traditionally made from kelp and dried shiitake, not bonito. Not every place using the word 精進 follows the old rules: some add honey, dairy or fish dashi. Usually a set course, often booking only, at fixed times. Traditional temple cooking also avoids onion and garlic, so it can taste gentle. That's on purpose.