Kale and Black Bean Tacos

1 T olive oil
1 small red onion, halved and thinly sliced
3 cloves garlic, minced
1 tsp ground cumin
1 small head kale (about 5.5 ounces), tough stems removed, cut in
large pieces
1 15 ounce can black beans, rinsed and drained
1 cup frozen corn kernels
2-4 ounces feta cheese, crumbled
8 6-inch corn tortillas
1/4 cup prepared salsa, or more to taste
1 medium avocado, cubed (optional)

In a large skillet, heat oil on medium heat. Add onion and garlic;
sprinkle with cumin. Stir to mix and saute for 2 minutes. Add kale to
skillet. Stir or turn with tongs to coat with oil. Cover and cook for
2 minutes until just tender and bright green. Add beans and corn and
cook for 2 minutes to warm through. Add feta and stir to mix. Season
with salt and pepper.

While kale mixture is cooking, warm tortillas.

Put mixture in tortillas and top with salsa and avocado.