Put the oil in a large skillet over medium-high heat. When it is hot, add the onion and garlic and cook, stirring occasionally until soft, about 3 minutes.
Add the cumin and tomatoes and adjust the heat so the sauce bubbles gently. Cook, stirring occasionally until the tomatoes begin to break apart, 10 minutes.
Stir in the edamame and sprinkle with salt and pepper. Cook until the edamame are tender, 5 to 10 minutes. Taste and adjust the seasoning. Scatter the cilantro on top and serve.