Step 1Place the shrimp, salt, fish sauce and Caramel Sauce into a shallow saucepan. Bring to a vigorous simmer over high heat. Add the yellow onion and pepper, stirring to evenly distribute. Continue cooking over high heat, occasionally turning the shrimp so that they're well coated with sauce. They'll curl up and release their juices to combine with the other ingredients and concentrate into a dark sauce. Add a little water if things get too dry.
Step 2The shrimp are done when they've taken on an orange-brown color and have a pleasant sweet chewiness, about 8 to 10 minutes after you've added the onion and pepper. There will be a few tablespoons of sauce in the pan. Remove from the heat, add the oil and stir to coat the shrimp. Scatter the green onion on top and serve with lots of steamed rice.