Fill a large pot half full with lightly salted water and bring to a rolling boil. Add corn cobs and return to a boil. Cook until corn is softened but still firm, about 5 minutes. Remove from pot; rinse with cold water until cool enough to handle. Cut kernels from the cob with a sharp knife; place into a large mixing bowl.
Place edamame into a large pot; pour in 2- to 3-inches of water. Cover; bring to a boil. Steam edamame until shells are softened, 2 to 3 minutes. Drain; let cool. Squeeze the center of each pod to pop the edamame out into a bowl.
Mix edamame, black beans, tomatoes, and onion into the corn kernels; season with salt and pepper.
Set oven rack about 6 inches from the heat source and preheat the oven's broiler. Line a baking sheet with aluminum foil; place jalapeno skin side up on the baking sheet.
Roast jalapeno in the preheated oven until outer skin is charred, about 5 minutes; mince with a sharp knife.
Combine olive oil, garlic, roasted jalapeno, lemon juice, cilantro, balsamic vinegar, and cumin in a bowl; whisk until well mixed. Pour over vegetable mixture; stir until vegetables are coated.
