In a dutch oven add oil, onion, carrots and celery with a pinch of kosher salt. Stir and cook over medium to medium-low until just about tender. About 8 minutes.
Add garlic, stir and cook 1 minute.
Next add potatoes, bay leaf, broth and 2 cups water. Cover and bring to a boil.
Once boiling, reduce to medium-low and quickly stir in the cabbage. Cover, with the lid askew, and simmer 10-15 minutes or until potatoes are tender and cabbage is soft.
Use a stick blender to puree the soup a little bit. You still want it chunky.
Add in cream, beer and corned beef.
To thicken, combine flour with 3 tablespoons hot soup liquids. Stir to make a paste. Add it into the soup, stir and simmer 15 mintues or until the chowder has thickened slightly.
Remove the bay leaf, season with kosher salt and black pepper to taste.
Serve with snipped chives and rye croutons if desired.