Add the lentils to a small saucepan and cover with cool water. Cover the pan and set over high heat. Bring to a boil, reduce the heat to medium-low and cook for 10 minutes. Drain.
While the lentils are cooking, add the lemon juice, mustard, honey and garlic to a large salad bowl. Whisk to combine. Whisking constantly, stream in the olive oil.
Add 2 tbsp of neutral oil to a large skillet (preferably cast iron). Set over high heat. Once the oil is near smoking, add the corn along with a generous pinch of salt. Cook the corn, stirring occasionally, until it begins to turn deep brown and char in parts, about 5-8 minutes.
Remove the corn from the heat and stir in the cumin, paprika and sumac along with a few generous grinds of black pepper. Add to the salad bowl with the dressing.
Add the cooked lentils, parsley, cilantro and oregano. Toss to combine. Taste to adjust for seasoning, adding more salt ad pepper if necessary.