Rinse the lentils under cold running water until the water runs clear. Set aside to drain.
Heat olive oil in a large pot over medium heat. Add the chopped onion, carrots, and celery. Cook for 5–7 minutes until softened.
Add the minced garlic, cumin, and turmeric. Stir for 1–2 minutes to release the aroma.
Pour in the chopped tomatoes and vegetable stock. Stir well to combine.
Add the rinsed lentils and bring the mixture to a gentle boil.
Reduce the heat to low and simmer for 25–30 minutes, stirring occasionally, until the lentils are soft and the soup thickens.
Taste and season with salt and black pepper as needed.
For a smoother texture, blend part or all of the soup using a hand blender. For a chunkier texture, leave as is.
Let the soup rest for 5 minutes before serving to allow flavours to settle and texture to thicken slightly.
Serve warm as a pre-meal satiety snack, ideally 20–30 minutes before your main meal.