To make the tomato soup: Add the olive oil to a saucepan over medium-high heat. Add onion and fry for 3 minutes.
Add ginger and Thai curry paste, stirring constantly, and cook for approximately 30 seconds. Add all of the remaining ingredients, except the Thai basil. Bring mixture to a boil, cover and reduce heat to a simmer. Simmer for 20 minutes.
Remove lemongrass stalk and stir in Thai basil.
Using a stick blender, blend the soup until creamy and smooth. Keep warm over low heat until ready to serve.
To make the grilled cheese: To assemble the grilled cheese, place 1 slice cheddar each on two slices of bread. Top with equal amounts of kimchi and sliced avocado. Top with a slice of jack cheese on each and finish with the remaining slices of bread.
Melt 2 Tablespoon butter in a large non-stick skillet over medium heat. Carefully add both sandwiches to the pan. Cooking until golden brown, approximately 5 minutes.
Remove sandwiches from the pan and add remaining butter. Once melted, return the sandwiches to the pan, toasted side up. Cook again until golden brown and the cheese is melted, approximately 5 minutes.
Serve immediately with soup.