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Red lentil tomato soup that is high in fiber and ready in 20 minutes

Red lentils are the fastest legume there is. They need no soaking and break down into a thick, creamy soup in 15 minutes, which makes them ideal for a weeknight when you want a high-fiber meal without effort.

Orange soup in a black ceramic bowl
Prep5 min
Cook15 min
Serves4
Fiber (est.)7 g

A bowl of this soup supplies about 7 g of fiber, and 14 g of protein.

This is one of our prediabetes recipes, and the total time is 20 minutes. To see why these foods help, read our guide to insulin resistance and prediabetes or the full overview of insulin resistance.

Red Lentil Tomato Soup

Soup

  • 1 tbsp (15 ml) olive oil
  • 1 onion, diced
  • 2 carrots, diced
  • 3 garlic cloves, minced
  • 1 tsp ground cumin
  • 1/2 tsp smoked paprika
  • 1 cup (200 g) red lentils, rinsed
  • 1 can (14 oz / 400 g) crushed tomatoes
  • 4 cups (950 ml) low-sodium broth or water
  • 2 tbsp lemon juice
  • Salt and pepper
  • Plain yogurt and chopped parsley, to serve

Method

  1. Heat the oil in a large pot over medium heat. Cook the onion and carrots for 4 minutes until softening.
  2. Stir in the garlic, cumin and paprika and cook 30 seconds until fragrant.
  3. Add the lentils, tomatoes and broth. Bring to a boil, then lower the heat and simmer, partly covered, for 12 to 15 minutes until the lentils are soft and falling apart.
  4. Stir in the lemon juice. For a smoother soup, blend a third of it with an immersion blender or mash with a spoon.
  5. Season with salt and pepper. Serve with a spoonful of yogurt and parsley.

Approximate per serving: 260 calories, 14 g protein, 7 g fiber. Values are estimates and vary with brands and portions.

Why this works for prediabetes

  • Soluble fiber and protein together. Lentils are among the best foods for flattening the blood sugar curve.
  • Acid helps too. Tomatoes and lemon add acidity, and a little acid at a meal is linked to a smaller glucose spike in small studies.
  • Easy to repeat. Eating legumes at lunch can also lower the blood sugar response at the next meal, a pattern researchers call the second-meal effect.

The same principles are explained in detail in our insulin resistance and prediabetes guide. For more ways to add fiber to meals, see the fiber guide.

Make it your own

  • Rinse red lentils until the water runs mostly clear, then they do not foam.
  • Freezes well for 3 months in single portions.
  • Add a handful of spinach in the last 2 minutes for extra greens.

More prediabetes recipes

Every recipe here avoids added sugar, refined flour and high-load fruit. Learn how glycemic index and glycemic load work.

Please note. This page is for education and is not medical advice. If you take insulin or medication that can cause low blood sugar, such as a sulfonylurea, talk to your care team before making large changes to what you eat. Read our medical disclaimer.

© 2026 Insulin Reset Kitchen. Information on this site is educational and is not medical advice. Talk to your doctor or dietitian before changing your diet or medication.