Combine the tamarind pulp and hot water, and let soak for 15 minutes. Using the back of a small spoon, mash the pulp until mushy. Push the juice and pulp through a sieve, scraping the pulp to extract as much flavor as possible. Set juice aside.
To make the vinaigrette, heat the 1/4 cup oil in a saucepan over moderate heat and add the shallots, garlic, lemon grass, and chili flakes and stir-fry until fragrant, about 1 minute. Remove from heat and add the sugar, rice wine vinegar, fish sauce, and the tamarind juice. Set aside.
To prepare the seafood, heat the 1 tbsp oil in a nonstick fry pan over high heat. Brown all the salmon pieces until just cooked, 2 to 3 minutes on each side. Transfer to a plate. If pan is dry, add additional oil. Continue by cooking the shrimp then the scallops until just done, about 1 minute or so on each side.
Just before serving, toss the greens and starfruit in the vinaigrette and portion onto individual salad plates. Top each plate with a piece of salmon and a couple shrimp and scallops. Scatter a few cherry tomatoes around the edge of each plate and serve.