If you have a wok, now's the time to use it, though a cast-iron skillet will also do the trick.
2 tsp. plus ¼ cup soy sauce
2½ tsp. cornstarch, divided
1½ tsp. sugar, divided
½ tsp. kosher salt, plus more
1 lb. skinless, boneless chicken thighs
2 or 3 Tbsp. sambal oelek (3 will be spicy and you can always add more at the end)
2 Tbsp. unseasoned rice vinegar
4 garlic cloves
1 2" piece ginger
4 celery stalks
4 oz. dates, preferably Medjool (about 5-7, I used about 10!)
1½ cups cilantro leaves with tender stems, divided
1/4 cup vegetable oil
¾ cup roasted, salted peanuts
Cooked rice to serve with the chicken.
Whisk together 2 tsp. soy sauce, 1½ tsp. cornstarch, ½ tsp. sugar, and ½ tsp. salt in a medium bowl; set marinade aside. Cut 1 lb. skinless, boneless chicken thighs into ½" pieces. Transfer to bowl with reserved marinade and toss to evenly coat. (The cornstarch will tenderize the chicken and lock in its juices.) Set chicken aside.
Whisk 3 Tbsp. sambal oelek, 2 Tbsp. unseasoned rice vinegar, remaining ¼ cup soy sauce, 1 tsp. cornstarch, 1 tsp. sugar, and ¼ cup water in a small bowl or measuring glass. (Here, the cornstarch serves the role of thickening agent.) Set sauce aside.
Using the side of your chef’s knife, lightly smash 4 garlic cloves, then peel and finely chop. Finely chop one 2" piece ginger (skins and all unless they scare you!) Combine garlic and ginger in a small bowl.
Trim roots from 6 scallions, then slice crosswise into ½" pieces. If there are any leaves attached to 4 celery stalks, remove and coarsely chop them; set side for serving. Cut stalks in half lengthwise, then crosswise into ½"-thick pieces. Tear open 4 oz. dates and remove pits; discard. Cut flesh into ½” pieces. Combine scallions, celery, and dates in a medium bowl.
Coarsely chop 1 cup cilantro leaves with tender stems. Reserve remaining ½ cup cilantro leaves with tender stems unchopped for serving.
Head over to the stove with all of your prep work (gathering it all on one baking sheet will make this easy!). This stir-fry comes together fast, so you want to be sure to have it all at the ready.
Combine ⅓ cup vegetable oil and ¾ cup roasted, salted peanuts in a large cast-iron skillet. Set skillet over medium heat and cook nuts, stirring often to encourage even toasting, until they are a few shades darker and fragrant, 5–7 minutes. Remove skillet from heat and, using a slotted spoon so you leave the oil behind, transfer nuts to a small bowl or plate.
Set skillet with oil over medium-high heat. Cook garlic and ginger, stirring constantly with a wooden spoon, until very fragrant but not yet browned, about 30 seconds.
Add reserved chicken and cook, stirring to break it apart, until it is no longer pink on the outsides, about 3 minutes . At this point, it will still be slightly undercooked inside, but it will cook a few more minutes with the remaining vegetables.
Add scallions, celery, and dates and cook, stirring often, until scallions are bright green and slightly softened, about 2 minutes. The celery should still be quite crisp and crunchy (taste as you go!).
Give reserved sauce a good stir to be sure cornstarch is incorporated (it loves to settle at the bottom), then add to skillet. Cook, stirring often, until sauce thickens and turns glossy and chicken and vegetables are evenly coated, about 2 minutes.
Remove skillet from heat and stir in fried peanuts and chopped cilantro. Taste stir-fry and add a little more salt if you think it needs it. Serve straight out of the skillet or transfer to a shallow bowl. Scatter reserved celery leaves (if you have them) and cilantro leaves over. Serve with rice alongside.