Step 1

Trim and rinse 2 bunches Broccolini under cool water and shake off the excess water. Peel and grate 1 (1-inch) piece fresh ginger into a small bowl. Whisk in 1/4 cup tamari or soy sauce and 2 tablespoons sesame oil.

Step 2

Pound 4 boneless, skinless chicken breasts one at a time: Place 1 chicken breast in a gallon-sized zip-top bag and pound with a rolling pin or the flat side of a meat mallet to an even 1/2-inch thickness. Pat dry with paper towels and season with 1/4 teaspoon kosher salt and 1/4 teaspoon black pepper.

Step 3

Heat 2 tablespoons olive oil in a 10-inch or larger skillet over medium-high heat until shimmering. Working in batches, add the chicken and sear until deeply browned, 5 to 7 minutes per side. Transfer the chicken to a plate.

Step 4

Add the Broccolini to the skillet and sauté until bright green and almost tender, about 10 minutes. Return the chicken and any accumulated juices to the pan. Pour in the sesame-ginger sauce and simmer until the Broccolini is crisp-tender and the chicken is cooked through, 2 to 3 minutes. Garnish with sesame seeds, if desired.