In a stock pot on medium heat add the olive oil, cook the onions, garlic, oregano and leeks until soft. Around 3-5 mins.
Add the potatoes and cook for another couple of mins.
Add the water and bring to a boil.
Add the milk and reduce the heat.
Cook on low flame until the mixture has reduced and everything is soft.
Blend the mixture and strain through a sieve.
Season the soup one last time and add the cheddar and stir around.
Serve it hot.
