Add the water, vinegar, and sugar to a medium-sized bowl. Stir until the sugar dissolves then toss in the shallots. Set the shallots aside to marinate while you prepare the salad. 

Place a fine-mesh strainer over a heatproof bowl. 

Add enough oil to a small skillet to get it about 1/4 inch deep. Heat the oil over medium heat and add the shallots. Cook the shallots for 5 to 8 minutes, stirring frequently to break them up. When the shallots start to get a light golden color, add the garlic and cook, stirring frequently for 3 to 5 more minutes until medium golden brown. 

Immediately pour the oil, shallots, and garlic through the sieve. 

Let the oil drain into the bowl and set the fried shallots aside. 

Prepare a bowl of ice water and set it aside.

Bring a pot of water to a boil and toss in a teaspoon of salt. Boil the shrimp for about 2 to 3 minutes or until you see them change color. The timing will depend on the size of the shrimp (see the notes if you want curly, spiraled shrimp, as we have in the photos).

Drain the shrimp and transfer them to the ice water to stop them from cooking. Transfer them to a salad bowl and pat them dry with paper towels.

Peel the mangoes and cut them into thin strips. Add the mango slices to the salad bowl with the shrimp.

Add the mint leaves, pickled shallots, and the nuac mam sauce. Toss the ingredients together.

Top the salad with the fried shallots and chopped peanuts.