Heat olive oil in a large saucepan over medium-high heat. Add onion, celery and carrot; cook and stir until onion has softened and celery and carrot are crisp-tender, 3 to 5 minutes. Stir in garlic, paprika and chilli flakes; cook until fragrant, about 1 minute.
Pour chicken stock, water and quinoa into the saucepan. Bring up to a simmer; reduce heat to medium-low, cover and cook until quinoa is tender, about 20 minutes.
Stir in tomatoes with juice, black beans and sweet corn. Bring back up to a simmer and cook, uncovered, until black beans are heated through, about 5 minutes. Season with salt and pepper.