For the Carrot Soup: In a pot over medium heat, add the olive oil. Once hot, add the chopped yellow onions and cook for 4 minutes until softened. Then, add the minced garlic and curry powder, cooking for 1 minute until fragrant. Next, add the carrots, chicken broth, the initial 1/2 TBSP of salt, and a pinch of pepper. Bring the mixture to a boil, then reduce the heat to a simmer and cook until the carrots are very soft, about 20-30 minutes. Carefully blend the soup using an immersion blender or by transferring it in batches to a regular blender until completely smooth. Season to taste with additional salt and pepper as needed.
For the Kimchi Grilled Cheese Sandwiches: Spread softened butter evenly on one side of each of the 8 slices of sourdough bread. Take one slice of bread and place it buttered-side down on a clean surface. Evenly layer a portion of the mozzarella cheese, kimchi, and sharp cheddar cheese on top. Cover with a second slice of bread, buttered-side up.
To cook the sandwiches: Heat a griddle pan or cast iron skillet over medium heat. Place a sandwich in the hot pan. Cook until the underside is a rich golden brown, which should take about 2-3 minutes. Carefully remove the lid if using one, flip the sandwich, and press it firmly with a spatula. Cook until the second side is evenly browned and the cheese is thoroughly melted inside, approximately 2 more minutes. Transfer the cooked sandwich to a cutting board and cut each sandwich in half.
To Serve: On a plate, arrange your sandwich halves. Serve alongside a bowl of the warm carrot soup. Garnish the soup with fresh chives and a dollop of creme fraiche or sour cream.
