Prepare a medium pot of boiling water to blanch green beans. Boil green beans for 5 minutes, then transfer to a bowl of ice water. This will stop the cooking process and help retain some texture to the green beans.
Heat a large pan on medium high heat. Add olive oil and sauté diced onion, celery, poblano, and mushroom for about 5 minutes until vegetables become soft and translucent.
Add sausage to the same pan and allow meat to brown. Once fully cooked add garlic, dried oregano, salt and pepper. Heat for another minute and then add the stewed tomatoes.
Add blanched green beans to the sausage mixture and stir to combine. Place a lid on the pan and simmer on low for 15-20 minutes to allow flavors to blend together.
