Short Ribs in slow cooker

1 medium onion, sliced
4 cloves garlic, peeled and crushed
1/4cup rice vinegar
1/4cup low-sodium soy sauce
2 tablespoons chopped fresh ginger
2 tablespoons light brown sugar
1 teaspoon crushed red pepper
3 pounds short ribs (preferably flanken)
2cups white rice
1/2pound snap peas, sliced

Combine the onion, garlic, vinegar, soy sauce, ginger, sugar, red pepper, and ¼ cup water in a 4- to 6-quart slow cooker. Add the beef and turn to coat. Cover and cook until the beef is very tender, on low for 7 to 8 hours or on high for 5 to 6 hours (this will shorten total recipe time). Skim off and discard most of the fat. Twenty minutes before serving, cook the rice according to the package directions.