Place chile in a spice or coffee grinder; process until finely ground (about 1 teaspoon).
Heat oil in a large nonstick skillet over medium-high heat. Add mustard seeds to pan; sauté 30 seconds or until seeds begin to pop. Add onion; sauté 2 minutes or until lightly browned. Stir in ground chile, garlic, and next 4 ingredients (through turmeric); cook 30 seconds, stirring constantly. Stir in potatoes; cook 2 minutes. Add 1/2 cup water and salt, and bring to a boil. Reduce heat to medium-low and simmer, covered, 8 minutes or until potatoes are tender. Add beans; cover and cook 5 minutes or until beans are crisp-tender. Stir in cilantro.