Warm up a large pot of salted water over low heat. Add corn and cook, about 15 minutes. Remove and let drain.
On a wood-fired or charcoal grill, nestle corn directly into the coals and grill on all sides until it reaches the level of char you desire.
Remove from heat and allow to cool slightly.
Mix 1 cup crema, salsa, and the juice of 2 limes in a small bowl, plus salt to taste. In a second small bowl, mix remaining crema, lime juice, and salt to taste.
To serve, shave kernels off one side of the corn and set aside. Place the cob kernel-less side down on a plate. Sprinkle kernels over top, then drizzle the first crema, then the second. Sprinkle with the grated cotija and sea salt.