In a large saucepan, heat 2 tablespoons of the olive oil. Add the shallot and cook over moderate heat, stirring, until lightly golden, about 5 minutes. Add the garlic and cook, stirring, until fragrant, 2 minutes. Stir in the lentils, thyme and 3 cups of water and bring to a boil. Cover and simmer over low heat until the lentils are tender and all of the liquid has been absorbed, about 30 minutes. Discard the thyme sprigs. Transfer the lentils to a medium bowl and let cool slightly. Stir in the lemon juice, 2 tablespoons of chives and remaining 1/4 cup of olive oil; season with salt and pepper.