Complex sentence: Glasswort is edible cooked (very nice steamed in a microwave steamer, and then coated in butter) or raw, and burnt glasswort was used as a source of soda for glassmaking.
Split into simpler sentences: Glasswort is edible cooked (very nice steamed in a microwave steamer, and then coated in butter) or raw. Burnt glasswort was used as a source of soda for glassmaking.