Bring a pot of water to a boil. Add green beans and cook 3–4 minutes until tender-crisp. Drain and set aside.
In a skillet, heat 1 tbsp olive oil over medium heat. Add sweet potato cubes and cook 8–10 minutes, stirring occasionally, until golden and mostly tender. Remove and set aside.
In the same skillet, add another tbsp olive oil and sauté eggplant for 6–7 minutes until soft and lightly browned. Remove and set aside.
Add the remaining tbsp olive oil. Sauté garlic for 30 seconds until fragrant. Stir in kale and cook about 3 minutes.
Return green beans, sweet potatoes, and eggplant to the skillet. Add tomatoes and cook another 5 minutes, stirring often, until everything is heated through and the tomatoes soften.
Season with salt, pepper, and optional red pepper flakes or lemon juice. Serve warm.
Makes 4 servings as a side dish or 2 servings as a light main dish.