Drain and rinse the canned black beans thoroughly, then transfer them to a large mixing bowl.
Preheat your grill or grill pan over medium-high heat until hot and slightly smoky.
Toss the corn kernels with a teaspoon of olive oil, salt, and pepper, then spread them on the grill.
Grill the corn for about 8-10 minutes, turning occasionally until they develop dark char marks and smoky aroma.
Remove the corn from the grill and let it cool slightly. Once cool enough, cut the kernels off the cob using a sharp knife, or scrape them off if using frozen corn.
While the corn cools, thinly slice the red onion and place it in a small bowl with the vinegar, a pinch of salt, and a dash of sugar. Let it pickle for at least 15 minutes, until it turns vibrant pink and tangy.
Add the grilled corn, cherry tomatoes, and pickled onions to the bowl with the beans.
In a small bowl, whisk together lime juice, olive oil, cumin, chili powder, salt, and pepper to make the dressing.
Pour the dressing over the salad and gently toss everything together until evenly coated and flavors meld.
Taste and adjust seasoning with additional salt, pepper, or lime juice if needed. Let the salad sit for at least 10 minutes to allow flavors to deepen.
Garnish with chopped cilantro and serve at room temperature or chilled for a refreshing, colorful dish.