In a large stock pot, over medium heat, add the olive oil and onions; cook until the onions are translucent.
Add the minced garlic, chili powder, cumin, salt and black pepper; sauté for just one minute.
Add the vegetable stock and water; stir to evenly disperse the spices and onions throughout the liquid.
Add the tomato paste, potatoes, carrots and celery; stir well and place a lid on the pot.
Allow to cook for 20 to 30 minutes, depending on how long it takes the carrots and potatoes to become fork tender.
Add the frozen corn and the canned diced tomatoes.
Allow the soup to return to a low boil; place the lid back on the pot and continue to simmer for 15 minutes.
Turn off the heat; stir in the parsley and allow the soup to sit for 5 minutes before serving.