Heat 2 tablespoons olive oil in a large skillet over medium-high heat. Add onion, lemon juice, garlic, and jalapeño; bring to a simmer and cook until onion softens, about 3 minutes.

Stir in eggplant, cumin, paprika, chili powder, black pepper, and seasoned salt; drizzle remaining 2 tablespoons olive oil over top. Cook, stirring occasionally, until eggplant softens and reduces in size, about 15 minutes. Serve in taco shells.