In a large pot, heat the olive oil over medium heat. Add the diced onion and sauté for about 5 minutes until translucent.
Stir in the minced garlic and cook for an additional 1 minute until fragrant.
Pour in the vegetable broth and add the diced potatoes and sliced carrots. Bring to a boil, then reduce heat and let simmer for 10-15 minutes, or until the vegetables are tender.
Add the frozen pierogi to the pot and cook for an additional 5-7 minutes, or until they are heated through.
Stir in the chopped dill, salt, and black pepper. Adjust seasoning to taste.
Serve hot, with a dollop of sour cream on top if desired.