Chop mushrooms, add 1 tsp salt, and boil for 5 minutes. Drain well.

Heat 2 tablespoons oil in a skillet. Add chopped onion and cook for 5 minutes until soft and translucent.

Transfer warm onion to a large bowl. Add bell pepper, coriander, vinegar, soy sauce, and sugar. Mix until combined.

Add mushrooms, paprika, sesame seeds, garlic, and chili. Toss to coat evenly.

Heat remaining 2 tablespoons oil until shimmering and carefully pour over the mushroom mixture. Stir well.

Add parsley and black pepper. Taste and adjust salt if needed.

Cover and refrigerate for 2 hours before serving.