In a large pot over medium heat, saute your onion, pepper, celery, and carrots in olive oil until the vegetables are softened.
Add in your minced garlic and saute for 30 seconds.
Add your diced tomatoes, peas, lentils, oregano, and broth. Add a big pinch of salt and bring to a boil.
Boil until your lentils are cooked through. About 20-30 minutes.
Once the lentils are cooked, turn off the heat and add the spinach. Mix the spinach in until it is wilted.
Serve immediately and enjoy!