In a large bowl, combine the lemon juice, mustards, egg yolk, capers, and sambal oelek. Drizzle in the oil, whisking constantly. Adjust the seasoning.
With a knife, finely chop the meat. Add to the dressing with the herbs and shallot and stir to combine. Season with salt and pepper. If desired, add sambal oelek, to taste. Serve the tartare with toasted baguette slices, homemade fries, and a green salad.