Start by preparing your broccolini. Saute or roast 2 bunches of broccolini in 1 tbsp avocado oil. To roast, preheat the oven to 415 degrees F, toss the broccolini in oil and sea salt, then roast on a baking sheet for 20 minutes. To saute, heat the oil in a large skillet over medium and add the broccolini and sea salt. Cover and cook 3 minutes, until broccolini is bright green. Remove the lid and continue cooking until broccolini reaches desired doneness, about 2 to 5 minutes. While the broccolini is cooking, prepare the fajitas. Allow broccolini to cool before transferring it to your meal prep containers.
Heat the avocado oil in a large cast iron or stainless steel skillet over medium heat. Add the onion and saute, stirring occasionally, until onion is transparent, about 5 minutes.
Add the remaining ingredients and stir well. Cover and cook 2 minutes. Remove the lid and continue cooking until some of the juices have burned off and chicken is cooked through, about 5 to 8 minutes.
Allow this mixture to cool so that you can transfer it to your meal prep containers.