Cantonese Sweet and Sour Lion's Mane Mushroom with Bell Peppers and Pineapple

Prepare Lion's Mane Mushroom. If fresh, gently squeeze out excess water, then tear into bite-sized pieces. If dried, rehydrate according to package instructions, then squeeze out all water. Toss mushroom pieces with a portion of cornstarch, salt, and white pepper until lightly coated.