Sorlarz is in fact Sir Lawrence who has been metamorphosed into an ogreish creature by his sister Queen Zinn so that she could have the throne. ("Sorlarz" presumably being a slurred attempt to pronounce Sir Lawrence.)
The heroes encounter Sorlarz when Eric attempts to steal a sack of his food. When he learns that the heroes are searching for the Garden of Zinn he directs them there against him better judgement and lets the poisoned Bobby rest in his forest hut with Sheila remaining behind. Sorlarz and Sheila make uneasy companions; she is grateful for his hospitality but he resents her meddling with his potions and opening a chest and discovering his royal apparel.
Queen Zinn's spell can only be broken by a tear of gratitude being shed on him and this happens when Sheila hugs him and cries after he saved the heroes from two phantom stalkers with an alchemical potion. Breaking the spell causes Queen Zinn to metamorphose into a similar ogreish creature.
(In the script Sorlarz is described as looking like a norker.)