For the soup, put the celery, carrot, jalapeno, onion, and tomatoes into large chunks. Place them in a blender with the garlic cloves, salt, and sugar. Puree the mixture until very smooth, then transfer to a soup pot. Turn the heat to medium and bring the soup to a boil, stirring every few minutes to prevent the soup from sticking. Simmer the soup for 20-30 minutes, uncovered, until you're ready to eat. Right before serving, taste and add more salt or pepper to your preference. Swirl the butter into the soup.