Heat oil in a pan over medium-high heat. Add onions and saute for 1-2 minutes, until the onions begin to become translucent.
Add bell pepper, corn, black beans and all the seasonings. Saute for three minutes.
Add tomatoes and saute for 30 seconds to 1 minute, just enough to heat the tomatoes through.
Turn off the heat and stir in the cilantro. Transfer to a bowl immediately, to prevent further cooking. Serve either warm or cold. Enjoy!