Dice butternut squash to cube shape. Season and toss with salt, pepper, and olive oil. Roast them over a large sheet pan lined with parchment for 25 to 30 minutes until the squash is tender, turning once with a metal spatula.
In the meantime, thinly slice the beef against the grain to ⅛-inch thin. Marinate the beef with ingredients from cumin to olive oil. Mix well and set aside in the fridge while preparing other ingredients. Prepare and gather the aromatics from scallions to chili peppers in one large bowl ready to use. Chop cilantro.
When the butternut squash is about 5 minutes away from done in the oven. Preheat a large skillet over medium heat, when hot, add 1.5 tbsp oil.
Spread the beef over the skillet in a single layer and pan sear over medium-high heat for about 3 minutes the first side without disturbing until the beef is crisp and brown. Cook the flip side about 1 minute. Pour the beef and the pan juices aside in one large bowl.
Start the skillet dry and while it’s still hot, add 1.5 tbsp oil. Saute aromatics in the bowl with 2 pinches of salt until fragrant, about 2 minutes. Add butternut squash and beef back to the skillet. Toss and taste to see if more salt is needed. Off heat, add cilantro and scallions. Toss everything together quickly while the skillet is still hot. Transfer to a large serving plate. Serve hot and immediately.
Sichuan peppercorns aren’t peppers at all. They are the dried husks of the fruit of the Chinese prickly ash tree. The flavor is citrusy and piney. There’s no perfect substitute to reproduce its numbing and tingly effect. Use a combination of whole black peppercorns and coriander seeds to mimic its flavor.
If this is your first time using Sichuan peppercorns, I personally prefer to use them in whole to fragrant the oil. Some recipes call for grind Sichuan peppercorns, if you use grind version, the flavor will be more intense. Please reduce the quantity to ½ tsp - 1 tsp.
You can substitute 2-3 Chinese whole dry red chili peppers with 1-2 fresh Fresno or serrano chili peppers. Remove the seeds and slice them into thin strips, lengthwise. For a non-spice version, thin slice half of one whole red bell pepper or skip the ingredient.
If making this dish in the winter, wrap the seared beef with a foil in the oven (unheated) to keep warm while sautéing other ingredients.
To keep this dish lower in carb, skip the butternut squash.