Cut each tofu block crosswise into 8 slices. Arrange tofu in a single layer on several layers of heavy-duty paper towels. Cover tofu with additional paper towels; let stand 15 minutes.
Heat a large nonstick skillet over medium-high heat. Coat pan with cooking spray. Add tofu; cook 2 minutes on each side or until browned. Set aside and keep warm.
Combine sugar and fish sauce, stirring with a whisk until blended. Heat oil in a small saucepan over medium-high heat. Add shallots and garlic; sauté 3 minutes or until lightly browned. Add lemongrass and chile; sauté 2 minutes. Stir in sugar mixture, and cook 1 minute. Serve lemongrass spread with tofu.