Start by preheating your grill or a stovetop grill pan over medium-high heat. Place the chicken breasts inside a zip-top plastic bag and gently pound them to an even thickness using a meat mallet or the heel of your hand. This helps ensure even cooking. Brush the chicken with 1 tablespoon of avocado oil, then coat both sides evenly with Southwest seasoning.
Grill the seasoned chicken for 5 to 6 minutes per side, closing the lid if using an outdoor grill, until the meat is fully cooked and no longer pink in the center. Once grilled, transfer to a cutting board and slice into thin strips.
Meanwhile, preheat your oven to 400°F. On a rimmed baking sheet, toss the zucchini slices and thinly sliced onion with the remaining tablespoon of avocado oil. Spread the vegetables into an even layer and roast for about 15 minutes, or until the zucchini is tender and beginning to brown around the edges.
To assemble, divide the roasted zucchini and onion mixture among serving plates. Top each portion with sliced grilled chicken and drizzle generously with tomatillo salsa.
In a nonstick skillet, fry the eggs until the whites are fully set and the yolks reach your preferred level of doneness. Place one fried egg atop each serving. Finish the plate with fresh tomato wedges, creamy avocado slices, and a few jalapeño rings for heat. Garnish with fresh cilantro if desired and serve immediately.