Position a rack in the upper third of the oven; preheat to 400 degrees F. Spread the almonds on a baking sheet and toast in the oven until golden, 6 to 8 minutes. Transfer to a plate and let cool.
Increase the oven temperature to 450 degrees F. Mix the parsley, vinegar, 2 teaspoons mustard, the garlic, 1/2 teaspoon salt and a few grinds of pepper in a bowl. Slowly whisk in the olive oil.
Transfer 1 tablespoon of the vinaigrette to a bowl and stir in the breadcrumbs. Set the pork on the baking sheet; season with1/2 teaspoon salt and a few grinds of pepper. Brush with the remaining 1 tablespoon mustard, then pat the breadcrumb mixture all over. Roast until the pork is golden and a thermometer inserted into the center registers 145 degrees F, 15 to 20 minutes. Let rest 5 minutes.
Meanwhile, put the peas and carrots in a microwave-safe bowl; add a pinch of salt and a splash of water, cover with plastic wrap and pierce a few times with a knife to vent; microwave until crisp-tender, 3 to 4 minutes. Let cool slightly. Add the watercress, almonds and the remaining vinaigrette. Slice the pork; serve with the salad.