Combine the pork cubes with the red pepper paste in a ziplock bag and massage. Add wine and mix. Seal bag and refrigerate for 24 - 36 hours.
Drain the pork in a colander set over a bowl to collect the liquid. Pat pork cubes dry with paper towels. Thoroughly rinse clams in the colander.
In a large wide-bottomed pot, warm 3 tbsp olive oil over medium-high heat. Add pork to pan in 2 or 3 batches. Brown cubes on all sides, about 5-7 minutes per batch. Add ⅛ cup wine and scrape up bits from bottom between batches. With a slotted spoon, transfer pork cubes to a plate when browned. Lower heat to medium and add onion. When soft after 5 minutes, add garlic and cook for another minute.
Pour reserved marinade into the pot and add pork cubes. Cover and cook 1 to 1½ hour over low heat.
While pork is cooking, preheat oven to 400° (200°C). Mix potato cubes in a bowl with 3 tbsp olive oil. Lightly salt and heavily pepper the potatoes. Put the cubes on a baking tray in one layer. Roast until they turn golden brown, about 45 minutes. Flip them a few times to be sure all sides brown.
When the pork has finished cooking, raise heat to high and stir in clams. Cover and cook 7-10 minutes. Throw away any that haven't opened. Taste broth and season as needed.
To serve, remove half the clams from their shells and return to pot, tossing the empty shells. Divide the potato cubes between bowls, top with the pork, clam, and broth from the pot. Sprinkle chopped cilantro on top. Bring out some good crusty bread for mopping up the sauce and a big bowl for the shells.