Heat the oil in a stockpot over MED heat, sauté to sweat onions and celery. Toss in a pinch of salt to coax out the liquids, stir occasionally 5-7 minutes to soften, until clear but not brown. Add garlic and stir 1 minute without browning.
Pour in the chicken broth and tomatoes, bring up the heat to HIGH and start to simmer the soup. Add the pepper, cayenne, and paprika. Stir in the rice and reduce the heat as it simmers. Cook for 30-45 minutes until the rice and vegetables are extremely soft. Season more to taste, particularly tasting for additional salt, and add the sugar for sweetness.
With an immersion blender, blend the soup 2-3 minutes until completely smooth. Serve the soup as is, or whisk in enough optional cream to your liking. If the soup is too thick, add additional broth or hot water. Heat through and serve in warm bowls, garnished with fresh cream, a parsley sprig or chopped basil, and croutons.