Slow Cooker Quinoa Black Bean Taco Soup
A hearty, smoky vegetarian taco soup that cooks itself: black beans, fire-roasted tomatoes, corn and chili-spiced broth simmer all day, then quinoa goes in at the end so it stays tender and fluffy instead of turning mushy. Finish with lime and your favorite taco toppings.
- Prep
- 25 min
- Cook
- 6 hr 45 min
- Wait
- 5 min
- Total
- 7 hr 15 min
- Makes
- About 10 cups (6 generous bowls)
Steps
Before you start
- Plan for about 7 hours: 6 hours on LOW, then 45 minutes on HIGH after the quinoa goes in.
- Use a 6-quart (5.7 L) slow cooker. A smaller one will be too full once the quinoa swells.
- Drain and rinse the canned black beans well to remove the starchy, salty canning liquid, but do NOT drain the canned tomatoes.
- Slow cookers vary. If yours runs hot, check the quinoa at 30 minutes.
Rinse the quinoa
- Place the quinoa in a fine-mesh strainer and rinse under cold running water for 30 seconds, rubbing the grains gently with your fingers.
- Shake well and set the strainer over a bowl to drain until you need it.
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Ready when: Water runs clear rather than cloudy or foamy.
Tip: Rinsing removes saponins, the natural coating that makes quinoa taste bitter or soapy.
Chop the vegetables
- Dice the onion and red bell pepper into ½-inch (1 cm) pieces, and mince the garlic.
- Drain and rinse the black beans in a colander under cold water.
- Mince the chipotle, if using.
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Ready when: Vegetable pieces are fairly even so they soften at the same rate.
Tip: Wear gloves or wash your hands well after handling chipotle.
Load the slow cooker
- Add the onion, bell pepper, garlic, black beans, undrained tomatoes, frozen corn, and chipotle (if using) to a 6-quart (5.7 L) slow cooker.
- Dollop in the tomato paste, then add the chili powder, cumin, smoked paprika, oregano, 1 teaspoon salt, and ½ teaspoon pepper.
- Pour in the broth and stir until the tomato paste and spices are fully dissolved with no dry clumps.
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Ready when: Broth is evenly red-brown and the spices are no longer floating in clumps.
Tip: Don't add the quinoa yet. Six hours of cooking would turn it to mush.
Slow cook the base
- Cover and cook on LOW for 6 hours.
- Don't lift the lid during cooking, since each peek adds 15–20 minutes of cooking time.
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Ready when: Onion and pepper are completely tender and the broth smells deeply of toasted chili and cumin.
Add the quinoa
- Stir the rinsed quinoa into the soup, making sure all of it is submerged.
- Turn the slow cooker to HIGH, cover, and cook for 45 minutes.
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Ready when: Quinoa grains are translucent, tender but with a slight bite, and a small white spiral tail is visible on each grain.
Tip: Check at 30 minutes. If grains are still opaque white in the center, keep cooking in 10-minute increments.
Season and brighten
- Stir in the lime juice.
- Taste and add more salt, a pinch at a time, until the flavors taste bright and balanced.
- If the soup is thicker than you like, stir in up to ½ cup (120 ml) hot water or broth.
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Ready when: Soup is thick but still spoonable, and tastes lively rather than flat.
Tip: Always salt after the quinoa is in. The soup thickens and the flavors concentrate as it cooks.
Rest and prep toppings
- Turn off the slow cooker (or switch to WARM), uncover, and let the soup rest for 5 minutes so it thickens slightly.
- Meanwhile, chop the cilantro, dice the avocados, shred the cheddar if needed, and lightly crush the tortilla chips.
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Ready when: Soup coats the back of a spoon.
Tip: Dice the avocado last so it doesn't brown.
Serve
- Ladle the soup into 6 bowls, about 1⅔ cups each.
- Top with avocado, cheddar, a spoonful of sour cream, cilantro, and crushed tortilla chips.
- Serve hot.
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Tip: Add the chips at the table so they stay crunchy.
Good to know
Tips
- Add the quinoa only for the last 45 minutes. Longer cooking makes it burst and turn the soup gluey.
- For a spicier soup, increase the chipotle to 2 tablespoons or add ¼ teaspoon cayenne.
- For more protein and body, stir in a cup of cooked shredded chicken with the quinoa, heating it through to 165°F (74°C).
- Lightly mashing about 1 cup of the beans against the side of the pot before adding the quinoa gives a creamier broth.
Make ahead
Chop the onion, pepper and garlic up to 1 day ahead and refrigerate in an airtight container. You can also combine all the base ingredients (everything except the quinoa and lime) in the slow cooker insert the night before, cover, and refrigerate; add 30 minutes to the LOW cook time if starting cold.
Storage & reheating
Cool completely, then refrigerate in airtight containers for up to 4 days. Freeze (without toppings) for up to 3 months; thaw overnight in the fridge. Quinoa continues to absorb liquid, so the soup will thicken. Reheat on the stovetop over medium-low heat or in the microwave, adding a splash of broth or water, until steaming hot.
Substitutions
- canned black beans → Pinto beans or kidney beans. Use the same amount, drained and rinsed. The flavor will be slightly milder.
- low-sodium vegetable broth → Chicken broth. Same amount; makes it non-vegetarian but works well.
- canned fire-roasted diced tomatoes → Regular canned diced tomatoes. Add an extra ½ teaspoon smoked paprika to make up for the lost smokiness.
- white or tri-color quinoa → Brown rice (parboiled) or small pasta. Rice needs about 1 hour on HIGH; small pasta only 15–20 minutes. Add extra broth as they absorb more.