I whipped this up to use up my leftover black beans. It was really good!

1 Tbsp chopped onion
1/2 cup green string beans, sliced
1/2 cup yellow string beans, sliced
1/2 cup black beans (I used canned)
1/4 cup crumbled feta cheese
2 Tbsp olive oil
juice from 1/4 lemon

Steam string beans and onion until cooked to desired consistancy (I like mine mushy, YMMV.) If serving hot: heat cooked string beans together with black beans. If serving cold, chill cooked string beans and black beans. Whisk together olive oil and lemon juice. Add beans. Mix well. Add feta, mix. Enjoy!

Makes two servings.
Per serving:
252 calories
18 g fat
17 g total carbs, 6 g fiber
8 g protein

You could always cut back on the black beans *or* use black soy beans (which I can't find anywhere ) to lower the carb count.