Lightly spray a nonstick 4-quart Dutch oven with vegetable oil and place
over medium heat. Add the onion, garlic, a few teaspoons water, and cook, stirring
constantly, about 5 minutes until the vegetables are tender.
Add 3 cups water, tomatillos, jalapeno and bouillon cubeand bring to a boil.
Reduce the heat and simmer 8 to 10 minutes. Cool slightly.
Transfer the mixture to a food processor, or use an immersion, or hand blender,
and puree until smooth. Return the mixture to the Dutch oven, stir in the orzo,
and heat through, but don't boil.
Either stir in the sour cream in the pot or add a dollop on each serving.