If I recall correctly, my sister enjoys spinach. I didn't think it much of a gamble to replace the spinach with organic rainbow chard in a basic saute of greens with onion and garlic. Sauteed greens fit well with nearly any savory meal, and my hosts seemed to agree that it was a nice element to complete their holiday dinner.
I knew that getting my hosts to enjoy kale would be more difficult, but fortunately, one of my favorite ways of eating the dark, leafy green--as kale chips--has already been approved by several other non-veg family members. Kale chips are not only easy to make, but addictively delicious. All I did was to clean, dry, and de-stem a small bunch of organic dinosaur kale, tear the leaves into small pieces, and toss them with a bit of olive oil, salt, pepper, and garlic powder. I spread them on a baking tray and placed them in the oven, preheated to 325 degrees Fahrenheit, and baked the kale until the leaves were crisp but not too brown, about 10 to 12 minutes. Despite looking and tasting nothing like chips as we traditionally know them, the kale was quite popular. Even my sister's boyfriend, who is a meat-and-potatoes type of guy, couldn't stop snacking on them.
I never try to force vegan ideals on anyone, just as my non-vegan family and friends never push their dietary lifestyles on me, but I admit that it was nice to have been able to successfully introduce something tasty and new into my hosts' diets. While it's not certain that they'll continue to eat those leafy greens regularly, I hope they will at least consider picking up some chard, kale, or other veggies on future farmers' market trips, because those greens are wonderful in so many ways.