How to Make It
In a large nonreactive saucepan, cook the bacon over moderately low heat until lightly browned and crisp, about 15 minutes. Transfer the bacon to a plate and pour off the fat. Add the olive oil to the pan along with the garlic and shallot and cook over moderate heat, stirring, until fragrant, about 2 minutes. Add the tomato halves and cook until warmed through.
Add the wine and simmer for 3 minutes, then add the clams. Cover and cook, stirring occasionally, until the clams open, about 12 minutes. Uncover, stir in the mustard greens and cook just until wilted. Gently stir in the bacon.
Ladle the ragout into 4 soup plates or shallow bowls and drizzle 1 teaspoon of olive oil over each serving.