Tomato Cheddar Soup

1) In a large heavy pot, melt the butter over medium heat.
2) Add the yellow onion and sweat for about 5 minutes or until the onion is soft and translucent.
3) Add the tomatoes and toss them with the butter and onions.
4) Let them steam for about 5 minutes.
5) Add the broth and bring to a simmer.
6) Put the lid on the soup and let everything simmer for about 20 minutes.
7) Puree the soup to smooth in a blender or using a hand blender.
8 ) Pour the soup back into the pot and simmer on low for about 10-15 minutes or until slightly thickened.
9) Then whisk in the cheddar cheese and stir until cheese is melted.
10) Season with kosher salt. And dish it into serving bowls.
11) Garnish with croutons and fresh chives.