Roasted Red Peppers Stuffed with Kale & Rice

8 ounces kale, (6 cups lightly packed), trimmed

1 tablespoon extra-virgin olive oil

1 medium onion, chopped

1/2 cup chopped red bell pepper

2 cloves garlic, minced

3/4 cup cooked short-grain brown rice

1/4 cup toasted pine nuts, divided

1 tablespoon lemon juice

1/4 teaspoon salt