Tomato and Shallot Braised Chicken with Capers

Name: Tomato and Shallot Braised Chicken with Capers
Ingredients: 1 1/2 Tbs. mustard seeds; 4 to 5 skin-on chicken leg quarters, about 4 lb. (2 kg) total; Kosher salt and freshly ground pepper; 3 Tbs. olive oil; 2 small shallots, thinly sliced; 3 Tbs. capers, drained; 3 Tbs. tomato paste; 1 1/2 tsp. Dijon mustard; 1 Tbs. plus 1 tsp. minced garlic; 1 cup (4 fl. oz./125 ml) white wine; 2 cans (each 28 oz./875 g) diced tomatoes; 2 cups (8 fl. oz./250 ml) chicken stock; 3 sprigs fresh basil, including stems and leaves; 2 Tbs. butter; 2 Tbs. Calabrian chile paste, plus more as desired; Chopped fresh basil for garnish