Have all your ingredients prepared and ready before starting. Place the cauliflower florets in the bowl of a food processor and pulse until cauliflower pieces are pea-size. Set aside. (This can be done ahead of time, just refrigerate) Heat a large skillet to medium-low heat. Add chopped walnuts and toast until fragrant, about 2 minutes, stirring to keep walnuts from burning. Transfer to a bowl.
In the same skillet, heat sesame oil to medium heat. Add cauliflower, onion and jalapeno (if using) and sauté 5-6 minutes or until soft. Stir in garlic, ginger and walnuts and sauté an additional 2 minutes. Add the soy sauce, lemon or lime juice with zest, and honey. Increase heat to medium-high and simmer 3-4 minutes, stirring frequently, until thickened. Stir in cilantro (if using.)
Scoop mixture into lettuce leaves or warm corn tortillas. Top with diced avocado, mango dressing or plum sauce if desired.
