Cut stems from chard leaves, chop stems, and squeeze out excess moisture in a towel. Set aside.
Fill a sauce pan with water and salt to taste. Bring to a boil. Blanch the cauliflower until tender. Remove and drain. Blanch chard leaves in the same water until cooked through. Remove and drain. Chop cauliflower and chard leaves to a medium size. In a towel, squeeze excess moisture out of chard leaves and cauliflower.
In a sauté pan, heat 1 tablespoon peanut oil and sauté chopped chard stems and diced onion together until cooked through. Set aside.
Pour 2 inches of peanut oil into a heavy bottomed, high-sided pan. Heat to 340°.
In a small bowl, combine flour, baking powder, salt, and cumin.
In a large bowl, whisk together egg yolks, buttermilk, and oil.
In a separate bowl, whip egg whites until stiff.
Add flour mixture to the egg yolk mixture along with all the cooked chard, cauliflower, chard stems, and onion. Fold in egg whites.
Using a teaspoon, drop batter into hot oil. Don’t overcrowd. When golden brown, remove from oil with a slotted spoon and place on paper towels. Repeat until all batter is used.
Serve hot with a dipping sauce of yogurt with lime zest.