In saucepan, heat water over medium-high heat; cook onions and garlic for 2 to 3 minutes, stirring often, or until starting to soften. Add chili powder; cook, stirring, for 30 seconds. Add tomato paste; cook, stirring, for 1 minute. Add broth and salt. Bring to a simmer over medium-high heat. Stir in quinoa and black beans; reduce heat to low, cover and cook for 20 minutes.
Let stand off heat, covered, for 5 minutes. Fluff with fork. Serve garnished with lime wedges and coriander sprigs, if desired.
