Remove the clams from the refrigerator, scrub them under cold running water, put them in a large bowl or clean sink, and cover with cold water. Clams need at least ½ hour in the water to release any sand trapped in their shells.
In the meanwhile, over medium-high heat, heat the olive oil in a large sautée pan or stovetop casserole.
Add the chopped onion, and cook slowly until the onions are softened and translucent, but not browned, about 15 minutes.
Add the wine and reduce by half. Remove from the heat and reserve.
While the onions are cooking, make the Spicy Orange Cilantro Butter. In a processor, combine the butter, orange zest, cilantro, garlic, paprika, red pepper flakes, and salt. Pulse to finely chop and combine the ingredients. Reserve.
To prepare the clams, put the pan with the sautéed onions back on the stove over medium-high heat, add the scrubbed clams, and cover. After the liquid comes to a boil, it will take about 5 minutes for the clams to open. As soon as most of the clam shells are open, remove from the heat. Remove any clams that did not open.
NOTE: Clams become tough when overcooked. Be sure to remove them from the heat as soon as most of them are open. You can also remove those clams that are open and give the remaining clams a few more minutes to see if they will open too.
Quickly combine the clams with the Spicy Orange Cilantro Butter, garnish with chopped cilantro and orange peel, and serve with plenty of hot, crusty bread.