In large pot, heat 1 tablespoon oil over medium-high heat. Add onion, tomatillos and garlic and cook, stirring often, until beginning to soften, about 5 minutes. Stir in 4 cups (or 2 pkgs.) corn, 3 cups broth, peas and chopped cilantro. Puree mixture using an immersion blender or in batches using a food processor or blender.
Wipe out pot, then heat remaining 1 teaspoon oil over medium heat. Add bell pepper and cook, stirring often, until softened, about 5 minutes. Return puree mixture to pot and bring to a simmer. Stir in chilies (with liquid), sugar, remaining corn and remaining 1 cup broth. Bring to a boil, reduce heat to low and simmer 15 minutes. Season with salt and pepper. (Can be prepared up to 2 days ahead; cover and chill.)
Ladle soup into bowls, garnish with cilantro and serve.