Use a food processor to pulse together half of the onion, cherry tomatoes, Thai seasoning paste, tamarind chutney, turmeric powder, red curry paste, soy sauce, white sugar, lemon juice, and lime juice until smooth.
Melt one to two tablespoons of ghee in a wok over high heat. Add the remaining sliced white onion and sauté until browned and beginning to caramelize.
Pour in the onion and spice mix. Stir occasionally until the sauce begins to separate solids from liquids, then let simmer for one to two minutes. Pour in the coconut milk, stir well, and return to a simmer.
If using scallops, sear quickly on both sides until browned.
Toss the uncooked shrimp and seared scallops into the sauce and simmer for an additional one to two minutes until pink and cooked through.
Serve over your favorite rice and enjoy!