Wiggly Meaty Octo Awesome

Octopus:

1 1/2 pounds cleaned octopus tentacles

1 cup plus 1/2 teaspoon kosher salt

1 cup chicken stock

1 large yellow onion, quartered

2 cloves garlic, smashed

1 one-inch piece fresh ginger, sliced

1 lemon, halved

3 tablespoons soy sauce

2 tablespoons olive oil

2 tablespoons sambal chile paste

1 teaspoon crushed red pepper flakes

1/2 teaspoon ground black pepper

Sauce:

2 tablespoons oyster sauce

2 tablespoons rice wine vinegar

1 tablespoon minced garlic

1 tablespoon minced fresh ginger

1 tablespoon sesame oil

1 teaspoon sambal chili paste

Vegetable oil, for the grill pan

Salad:

2 tablespoons vegetable or peanut oil

1 1/2 tablespoons rice wine vinegar

1 teaspoon sesame oil

Kosher salt and ground black pepper

1 bunch watercress

2 cups thinly sliced Napa cabbage

1 red bell pepper, thinly sliced

1 English cucumber, thinly sliced

1/2 red onion, thinly sliced

1 teaspoon grated lemon zest