Place a 6-quart pot or Dutch oven over medium heat. Once warm, add 1 tablespoon olive oil. When the oil shimmers, add the diced onion, celery, and carrots. Stir and cook for 5–6 minutes, until softened.

Add the tomato paste and stir to coat the vegetables. Cook for 1–2 minutes to deepen the flavor. Stir in the salt, black pepper, and Italian seasoning.

Add the chopped red bell or red sweet pepper and sliced garlic. Stir to combine and cook for about 3 minutes, stirring frequently to prevent the garlic from burning.

Pour in the vegetable stock, scraping up any browned bits from the bottom of the pot. Stir to combine.

Add the rinsed lentils and stir. Bring the mixture to a gentle boil, then reduce heat to maintain a steady simmer. Cover and simmer for 20 minutes.

Remove the lid, stir, and taste for seasoning. Adjust salt and pepper as needed. Stir in the apple cider vinegar. Continue simmering uncovered for 5–10 more minutes, or until the lentils are tender. If you prefer a more brothy soup, add more stock or water until you reach the desired consistency.

Taste once more and adjust seasoning if needed.

Serve topped with fresh herbs and a drizzle of olive oil. Enjoy!