Heat a large pan over medium-high heat. Drizzle with olive oil and add onion to the pan, mixing for about 3 minutes.
Add ground chicken to the pan with the onion, breaking apart, and cooking for about 2-3 minutes.
Once the ground chicken is halfway done add the mushrooms, white parts of the green onions, garlic, and ginger. Cook for another 3 minutes.
Turn the heat down to low and add the soy sauce, hoisin sauce, and sriracha mixing until incorporated and warm.
Turn off the heat and stir in the cashews.
Wash and dry the Romain lettuce. Lay the lettuce on a plate and fill them with the ground chicken mixture. Top with the green parts of the green onion and enjoy!
Notes
If you still want a nice crunch but don't have cashews you can use one small can of drained and chopped-up water chestnuts instead!