Heat the olive oil in a large saucepan set over medium heat. Add the onions and red bell pepper. Sauté until tender, about 5 minutes.
Stir in the garlic and taco seasoning. Cook for 1 minute. Add the tomato paste and sauté for 2 to 3 minutes. Don't skip this step - it helps to mellow the acidity of the tomato paste.
Add the corn, rotel, quinoa and vegetable broth.
In a bowl, mash the pinto beans with the back of a fork or a mini masher. They don't need to be perfectly smooth. Add to the soup.
Bring the soup to a boil, cover the saucepan and reduce the heat to medium-low (or whatever heat is appropriate on your stovetop to maintain a simmer). Cook for 20 minutes or until the quinoa is tender.
Add the black beans and simmer for 5 minutes. Stir in the cilantro. Serve.
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Notes
If you don't have access to rotel, combine canned diced tomatoes and canned diced green chiles. The more diced chiles you add, the spicier the mixture will be.Please note that I am not a medical or nutritional professional. I provide nutritional information for my recipes as a courtesy to my readers. It is calculated using the built-in recipe card calculator. While I attempt to provide information that is as accurate as possible, you should calculate the nutritional information independently before relying on it.