Prepare the Dressing: In a large mixing bowl, combine the fresh lime juice, avocado oil, and grated garlic. Sprinkle in the ground cumin, sea salt, and several twists of freshly ground black pepper. Whisk these ingredients briskly until the dressing is smooth and well blended, ensuring the oil emulsifies evenly with the lime juice.
Combine the Salad Base: Add the rinsed black beans and raw corn kernels to the bowl with the dressing. Toss gently to coat all the beans and corn with the zesty dressing, allowing the flavors to meld together.
Add Vegetables and Herbs: Incorporate the diced red bell pepper, chopped cilantro, jalapeño (or serrano), and finely diced red onion into the bowl. Carefully mix everything to distribute the fresh vegetables and spicy heat evenly throughout the salad.
Fold in Cheese and Avocado: Gently fold in the crumbled Cotija cheese and diced avocado, taking care not to mash the avocado. Taste the salad and adjust seasoning if needed, adding extra salt, pepper, or lime juice to suit your preference.
Finish and Garnish: Transfer the salad to a serving dish or keep it in the bowl. Sprinkle with additional cilantro leaves and toasted pepitas, if desired, for a final touch of flavor and crunch. Serve immediately for best freshness.