Combine water, chilies, green onions, thyme, garlic, salt, bay leaf and allspice in a large saucepan. Bring to boil then reduce heat, cover and simmer 10 minutes
Add shrimp and bring to boil
Remove the pan from heat let stand until cooked through about 10-15 minutes. Drain shrimp, discarding the liquid
Transfer the shrimp to a bowl and add the red onion and sliced mango
Whisk together all the dressing ingredients and drizzle over.
Toss well and serve