In a Dutch oven, cook a medium onion with three tablespoons of olive oil until soft.
Add two cloves of garlic and cook until fragrant.
Now open a can (28 oz) of peeled Roma tomatoes.
Place the tomatoes in a blender with the onions, garlic, about two teaspoons of fresh thyme leaves, and a cup of Clamato Tomato Cocktail.
Blend until smooth.
Transfer to the Dutch oven and let it simmer for about 25 minutes. Season with salt and black pepper.
Make the grilled cheese croutons by generously buttering one side of slice of bread ( I like sourdough bread for this) and place butter-side-down onto a preheated skillet. Sprinkle with cheddar cheese. Butter another slice of bread and place butter-side-up on top of the sandwich.
Grilled until lightly brown and cheese is melted.
Cut into small bite-sized pieces to garnish your soup.