How to Make It
In a food processor, process the parsley and olive oil to a puree. Let the puree stand at room temperature for at least 10 minutes or for up to 1 hour, then strain it through a coarse sieve. Season with salt and pepper.
Put the tomatoes in a large, nonstick skillet, cut side down, and cook over moderately high heat until charred, about 3 minutes. Transfer the tomatoes to a plate to cool slightly, then cut them lengthwise into 1/4-inch wedges.
Heat the olive oil in a large saucepan. Add the garlic and cook over low heat until fragrant, about 2 minutes. Add the wine and lemon juice and boil over high heat until almost evaporated, about 4 minutes. Add the clam juice and bring to a boil. Add the clams, cover and cook until they begin to open, 3 to 4 minutes; using tongs, transfer the clams to a warm bowl as they open.
Add the tomatoes and ham to the clam broth and season with salt and pepper. Pour the broth over the clams and sprinkle with the chopped parsley. Serve in warmed bowls and pass the parsley oil at the table.