For the meatballs- In a large nonstick skillet, heat olive oil over medium heat. Saute onion and kale in hot pan for 4 minutes or until onion starts to brown and kale wilts. Add in garlic and cook another minute until fragrant. Remove from heat and pour into a large bowl. Mix cooked veggies with ground beef, egg, milk, breadcrumbs, salt and pepper until well incorporated. Using a cookie scoop, portion meat mixture out into evenly sized meatballs. Roll in between your hands to create perfectly formed meatballs.
In the same nonstick pan you cooked your veggies, add 1 tablespoon olive oil and heat over medium. Working in batches, brown meatballs on 2 sides. Spoon meatballs out of pan and onto a plate.
For the glaze- While you are browning your meatballs, whisk all ingredients for teriyaki glaze together in a medium sized bowl.
After meatballs are all browned, pour out any excess grease from the pan. Replace pan to heat and stir in the glaze. Whisk to pick up any brown bits off the bottom of the pan and bring to a simmer to thicken slightly. Pour meatballs back into pan and stir to coat in glaze. Cover and simmer gently for 10 minutes or until meatballs are cooked completely through.
For the Salsa- While meatballs finish cooking, make the salsa. Prepare and toss all ingredients together, adjusting the seasonings to your preference.
To serve, add meatballs overtop rice or quinoa {or plain}. Add as much salsa as desired and top with lime wedges and extra cilantro.