How to Make It
In a large saucepan of boiling water, blanch the tomatoes until the skins just start to wrinkle, about 45 seconds. Drain and transfer to a bowl of ice water to cool. Peel the tomatoes and coarsely chop them.
In the large saucepan, heat the 1/4 cup of olive oil until shimmering. Add the shallots and cook over moderate heat until softened, 4 minutes. Add the wine and bring to a boil, then stir in the mussels. Cover and steam until they just start to open. Stir in the tomatoes, cover and cook, shaking the pan, until the mussels are open, 3 to 5 minutes longer; discard any that don’t open. Stir in the vinegar, sambal oelek and chopped tarragon and season with salt and pepper. Pile the mussels and tomatoes in a large serving bowl and pour in the juices from the pan. Drizzle with olive oil, garnish with tarragon leaves and serve with crusty bread.