Start the soup base: Set a large soup pot or Dutch oven on the stove over medium heat. Add the olive oil and heat it for about 1 minute, until it looks loose and shiny.

Add the chopped onion, diced carrots, and diced celery to the pot. Cook, stirring often, for 6 to 8 minutes, until the vegetables soften and the onion looks translucent.

Add the minced garlic and dried oregano to the pot. Stir for about 30 seconds, just until the garlic smells fragrant.

Add the tomato paste to the pot. Stir it into the vegetables and cook for 1 minute, until it darkens slightly and coats the bottom of the pot.

Build the broth: Add the rinsed lentils to the pot. Stir for about 30 seconds so the lentils are coated with the tomato mixture.

Pour the crushed tomatoes and vegetable broth into the pot. Stir well and scrape the bottom of the pot with a wooden spoon so nothing is stuck there.

Add 1 teaspoon of the kosher salt and the black pepper to the pot. Stir to combine.

Raise the heat to medium-high and bring the soup to a boil.

Simmer until the lentils soften: Lower the heat so the soup stays at a gentle simmer. Cover the pot partway with a lid and cook for 20 minutes, stirring once or twice.

Check the lentils. They should be partly tender but still a little firm in the center.

Add the drained chickpeas and the sliced cabbage to the pot. Stir and press the cabbage down into the hot broth so it starts to wilt.

Keep the soup at a gentle simmer for 8 to 10 minutes more. The lentils should be fully tender, the cabbage should be soft, and the broth should look slightly thicker than when it started.