In a large cast-iron or other heavy-duty skillet, melt oil on medium-high heat. Once hot, add the peppers and cook, undisturbed, until they begin to char in places, 1 to 1-1/2 minutes. Sprinkle garlic evenly over peppers and continue cooking, stirring occasionally, until just tender, and garlic is caramelized (not burnt). Peppers should be charred on all sides. Carefully transfer peppers to a bowl or platter, sprinkle with salt, and sesame seeds, and lightly toss to coat. Squeeze lime over peppers and serve.