In a deep pot, boil potatoes uncovered until barely tender. *Drain, save cooking liquid. In a wide skillet sauté yellow and green onions in oil over medium heat. Remove from heat and pour into large (at least 4- quart), deep pot with lid.
Add liquid, seasonings, cooked potatoes, and remaining ingredients, except the corn kernels. Simmer, covered, for 30 minutes until stew thickens. (If stew isn't thick enough, mix in some corn meal.) Add corn kernels, cook ten more minutes uncovered, stirring often. Garnish with pepper flakes. Serve with toasted tortilla chips.