Heat oil in 6-qt. pot over medium-high heat. Add onions, peppers, celery and carrots. Cook, stirring occasionally, until tender, about 10 minutes. Add tomato sauce and garlic to pot; cook until fragrant, about 30 seconds more.
Pour water mixture into pot; bring to boil. Stir in potatoes and quinoa. Lower hear to medium low. Simmer, stirring occasionally, until potatoes and quinoa are tender, about 15 minutes.
Stir parsley into soup. Season soup with adobo; divide evenly among serving bowls.
For a soup that is extra delicious, make sure to cook the vegetables slowly so they become tender without browning. During this “sweating” process, the flavors of the veggies are fully extracted, which translates into to a flavorful broth.