In 3-quart saucepan, place potatoes. Add water just to cover. Heat to boiling; reduce heat to low. Cover and boil gently (simmer) about 15 minutes or until potatoes are fork-tender. Drain. Reserve 1 cup potatoes; return remaining potatoes to saucepan. In small bowl, mash reserved potatoes with fork.
Stir reserved mashed potatoes back into remaining potatoes in saucepan, along with broth, sugar, garlic salt, pepper, ground red pepper, corn and roasted red bell pepper. Cook over medium heat 5 minutes, stirring occasionally.
In small bowl, stir flour into milk with whisk until well mixed; stir into potato mixture. Cook over medium heat, stirring frequently, until mixture thickens and boils. Stir in cheese until melted. Remove from heat; stir in yogurt, cilantro and green onions. Serve topped with bacon and, if desired, additional green onions.