How to Make It
Finely chop peanuts in a food processor; set aside. Combine shallots, garlic, chiles, shrimp paste, and water in the food processor; process until smooth; set aside.
Place a wok over medium-low heat until hot. Add the oil, swirling to coat sides. Add shallot mixture and cook, stirring, until fragrant, 6 to 8 minutes. Add chopped peanuts, tamarind water, soy sauce, plum sauce, and sugar; stir until smooth. Simmer over low heat, stirring, until sauce thickens slightly, 2 to 3 minutes. Remove from heat.
Drain tofu; cut in half lengthwise, then into 4 equal slices crosswise; cut each slice in half diagonally. Place between paper towels and gently press out excess water.
In a wok, heat oil for deep-frying to 350° over medium-high heat. Add tofu and deep-fry, turning once, until golden on all sides, 3 to 4 minutes. Remove from oil and drain on paper towels.
To serve, arrange tofu on a serving plate and garnish with mung bean sprouts and red bell pepper. Reheat sauce just until warm and pour over tofu.
Dried shrimp paste and tamarind water are available Asian food markets.