Heat the olive oil in a large pot over medium heat. Add the chopped onion and cook until it softens.
Stir in the minced garlic, harissa paste, and cumin. Cook for one minute until the spices become fragrant.
Add the frozen mixed vegetables, chickpeas, vegetable broth, and diced tomatoes to the pot. Bring the mixture to a boil.
Reduce the heat to low and simmer for 15 minutes, stirring occasionally, until the vegetables are tender.
Taste and season with salt and black pepper. Ladle the soup into bowls, top with chopped parsley, and serve with lemon wedges on the side.