How to Make It
In a small skillet, toast the pine nuts over moderately low heat, stirring occasionally, until lightly golden, 7 to 9 minutes.
Meanwhile, roast the pepper over a gas flame, turning with tongs, until charred on the outside, about 5 minutes. Transfer to a bowl, cover with plastic wrap and let stand for 15 minutes. Peel, seed and chop the pepper.
In a food processor, combine the toasted pine nuts with the bell pepper, egg yolk, garlic, chile and vinegar and pulse to combine. With the machine on, drizzle in both oils until emulsified. Add the parsley, cilantro and lemon juice and pulse to combine. Season the aioli with salt.
In a large pot, combine the wine, shallots and celery and bring to a boil. Add the mussels, cover and cook, stirring occasionally, until the mussels open, 3 to 5 minutes. Using a slotted spoon, transfer the mussels to a rimmed baking sheet and let cool. Remove 1 shell from each mussel. Arrange the mussels in a single layer on a large platter. Spoon some aioli over the mussels and garnish with chives. Serve.