Bring a medium pot of salted water to boil and poach the shrimp by placing them in the hot water, making sure water comes to a boil again, if it stops. Shrimp are done cooking when thoroughly pink and cooked through or registering 145ºF with an instant-read thermometer, about 3 to 5 minutes. Drain shrimp then transfer to a plate and place in the freezer or fridge until just chilled, about 10 to 20 minutes.
Meanwhile, make the citrus vinaigrette and prepare the fruit by combining the lime zest, lime juice, lemon juice, shallots, coriander, cumin and chili flakes in a large bowl.
Slice the tips off the oranges and place oranges flat on a workspace. Using a sharp paring knife (sharp is very important here), make top-to-bottom curved cuts, slicing just the peel and pith off and exposing the flesh. Then slice oranges into thin discs and set aside. Peel the mango, slice into 1½-inch chunks and set aside.
Pour the olive oil into the citrus vinaigrette bowl, add the cooled shrimp and rice and toss to coat well. Toss in the orange discs and mango chunks then gently toss in the arugula. Season with salt.
Serve the salad in the bowl or on plates with scoops of avocado and more salt on the avocado.