If you’re looking to season your stoneware for better flavor when cooking, then you’ll only want to wash the pieces with hot water and no soap. This will allow oils baked on it to build up and create a layer that protects the stoneware with each use and makes it easier to clean off food. This seasoning process is simply a way to create a corrosion- and stick-resistant coating using natural means.
That being said, if you have some food buildup that’s tough to clean, we’d recommend using a good set of nylon pan scrapers. Look for a set with rounded edges so you can easily reach corners or tight spots. Soaking your pan in hot water for a half-hour and then using a scraper can help get it clean while keeping the seasoning intact.