Heat 1 tablespoon oil in a wok or skillet and saute eggplant in batches on both sides until browned, 3 to 5 minutes per side, adding more oil as needed.

Combine cilantro roots, onion, chile peppers, garlic, sugar, lime juice, and fish sauce in a mortar; crush with a pestle into a soft paste.

Heat 1 tablespoon oil in a wok or skillet over high heat, add curry paste and stir-fry for 1 minute. Add eggplant, cover, and cook for 3 minutes. Mix in tofu and Thai basil.