In a medium sauce pan cook the 1/2 cup onion and garlicin hot oil until tender but not brown. Carefully stir in beans, undrained tomatoes, salsa, and salt. Bring to boiling; reduce heat. Simmer, uncovered for 15 minutes.
2
To serve mound rice on serving plates; make a well in each mound. Spoon the black bean mixture into wells. If desired, sprinkle with shedded cheees and a 1/4 cup of chopped onion.