In a small saucepan, saute together the vegetable oil, shallots, garlic, and dried pepper flakes over medium heat until the mixture releases its aroma and becomes confit-like in consistency. Add the coconut milk into the shallot mixture and heat through. Remove from heat and set aside to cool.
In a frying pan over medium-low heat, dry toast the desiccated coconut flakes until they turn medium brown color. Be careful not to leave the skillet unattended; coconut burns very easily. Set the toasted coconut aside to cool.
With a little bit of vegetable oil (2 tablespoons), sear the scallops in a saute pan for 2-3 minutes on each side or until golden brown, remove from the pan, and set it aside.
Gently break up the pomelo segments into roughly 1/2-inch pieces and put them in a large mixing bowl.
Add the shallot-coconut mixture, toasted coconut flakes, peanuts, and coriander leaves to the pomelo bowl.
Add to the mixing bowl 2 tablespoons each of the lime juice and fish sauce and toss everything together as gently as you can with your hands. Adjust the seasoning with more lime juice or fish sauce as needed. Serve immediately with seared scallops and additional roasted peanuts and toasted coconut on top (if desired).
Recipe contributed as part of the Senses of Thailand promotion at Selfridges.