Rinse and scrub the Littleneck Clams under cold water and, if time allows, soak them in a bowl of cold water for 20 minutes to purge sand; drain and set aside.
In a large Dutch oven or heavy pot, cook the Bacon over medium heat until crisp; transfer the bacon to a plate lined with paper towel, leaving the rendered fat in the pot.
If the pan is dry after removing most bacon fat, add a splash of Olive Oil and warm it over medium heat.
Add the chopped Onion, Celery, Carrot and Green Bell Pepper to the pot and sauté until softened and beginning to color, about 6–8 minutes.
Stir in the minced Garlic and the Tomato Paste and cook 1–2 minutes to deepen the paste's flavor.
Pour in the Clam Juice, a cup or two of Water (enough to make a flavorful broth), and add the Diced Tomatoes. Stir in the diced Potatoes, Bay Leaf, Dried Thyme, Dried Oregano, a pinch of Red Pepper Flakes, Kosher Salt and freshly ground Black Pepper.
Bring the pot to a gentle boil, then reduce heat and simmer, uncovered, until the potatoes are tender, about 15–20 minutes.
Return the reserved bacon to the pot (crumble or chop it first), then add the prepared clams and cover the pot; simmer gently until the clams open, about 5–7 minutes. Discard any clams that do not open.
Taste and adjust seasoning with more Kosher Salt or Black Pepper as needed. Stir in chopped Parsley and finish with a small drizzle of Olive Oil before serving.
