Bring a large, wide pot of salted water to a boil and cook the fregola for 8 minutes until al dente but not overcooked. Drain and rinse and set aside. Wipe out the pot and return to the stove.

Trim and remove the seeds of the chili peppers. Note: Keep the seeds if you want a spicier chili oil. Juice and zest the lemon. Peel the garlic cloves. Combine the peppers, lemon juice and zest, garlic, and onion in a food processor and pulse until finely minced.

Add the oil, sugar, and salt and pepper and pulse until combined. Transfer to a small saucepan and turn the heat to very low. Simmer the oil as you prepare the rest of the recipe, stirring occasionally. Taste and season to your preference (more salt, sugar, lemon juice, etc.).

Soak and scrub the clams. Thinly slice the remaining Vidalia onion. Cut the tomatoes in half.

In the pot used to cook the pasta, add the pancetta and turn the heat to medium. Cook, stirring regularly, until the fat has rendered and the pancetta is crispy, about 8-10 minutes. Remove the pancetta with a slotted spoon and transfer to a bowl.

If the pot seems too dry, add 1 tablespoon of oil and keep the heat on medium. Add the Vidalia onion and cook, stirring often, until well browned, about 10-15 minutes. Remove and transfer to a bowl. Turn the heat to medium-high and add the tomatoes, cut side down, and cook without moving for 5-8 minutes or until charred. Transfer the tomatoes to the bowl with the onions.

Keeping the heat to medium-high on the pot, add the white wine and scrape up any browned bits stuck to the bottom. Add the stock, 1 tablespoon of the chili oil, and the butter and bring to a boil. Add the clams and cover. Cook for 5-6 minutes and remove any opened clams.

Cover and cook an additional 1-3 minutes until the remaining clams have opened. Discard any clams that haven't opened.

Bring the broth back to a boil and cook for 6-8 minutes or until reduced slightly. Taste and season with salt and pepper. Add the tomatoes and onions back to the pot and stir to combine. Remove from heat.

Divide the fregola between bowls and ladle the broth with the tomatoes and onions over top and arrange clams on top of each dish. Spoon a teaspoon of the chili oil on top of each dish, if desired, and sprinkle with the crispy pancetta.