Cook Thai noodles as directed on package. Drain and set aside, covered.
While noodles are cooking, cut eggplant into 1/2-inch thick rounds; peel sweet potato and cut into 1-inch cubes. Dice pepper and tomato, chop onion, and mince garlic. Place all vegetables aside separately.
Heat oil in a large skillet or wok over medium heat. Add onion, garlic, and curry paste to hot oil and stir together, cooking for 20-30 seconds.
Add eggplant, potato, and pepper; stir and cook for 1 minute. Mix in tomato, milk, sugar, and soy sauce. Bring to a boil and then reduce heat to low. Cover and simmer 10-12 minutes, stirring occasionally until vegetables have softened.
Stir in cooked noodles, spinach, 1 teaspoon of lime zest, and 1 tablespoon of fresh lime juice; toss to coat evenly and continue to cook until heated through.
Serve with frozen mango on the side.