Rib Roast with English Mustard and Fresh Herb Dressing

finely chopped fresh basil

finely sliced fresh chives

finely chopped fresh flat-leaf parsley

small red chiles, such as Thai bird, seeded and finely chopped

garlic, finely chopped

plus 1 tsp. red-wine vinegar

plus 1 tsp. English mustard, such as Coleman’s

plus 1 tsp. capers, drained and rinsed

extra-virgin olive oil

Kosher salt and freshly ground black pepper

4-bone standing beef rib roast (8 to 9 lb.)

medium shallots, peeled and halved

medium red onions, peeled and quartered

garlic, peeled

sprigs fresh rosemary

olive oil

Kosher salt and freshly ground black pepper

English mustard, such as Coleman’s