At least 2 hours before, season the beef with salt and pepper. Whisk together the oil, sugar, chipotle pepper, adobo sauce and garlic cloves in a bowl. Add the beef to a baking dish or ziplock bag and pour the marinade ingredients overtop. Refrigerate for at least 2 hours or even overnight.
When you’re ready to cook the beef, heat a large skillet or wok over high heat. (as a note, I do not add the marinade to the skillet – I remove the beef with kitchen tongs and whatever marinade is on the beef comes along. The rest is discarded.) Add the coconut oil and once melted, add the beef in 2 or 3 batches. You don’t want to crowd the beef and you only want to cook it for a few minutes so it stays tender. Sear the beef for 1 to 2 minutes, then flip and sear the other side. Remove the beef and place in a bowl – and repeat with remaining beef.
Once all of the beef is in the bowl, reduce the heat to medium-high. Add in the peppers and onions and stir well to coat, scraping any bits off the bottom. Cook until the vegetables just start to soften, about 2-3 minutes. Reduce the heat to low, add the beef back to the skillet and toss. Cover and let sit over warm heat for 5 to 10 minutes so the flavors can marry a bit. Serve immediately with the coconut jasmine rice.