Roast the corn cobs over an open flame grill until you have nice “scoring” all over. Then use a knife to slice the corn kernels off the cob. (Roasted canned corn is an easy substitute.)
Roasted red pepper can be done fresh on the grill, too, or it's easy to find in a jar at any grocery store. Make sure it is not pickled or preserved in any way. You want the flavor of the pepper not their brine.
Rinse canned beans thoroughly. (I like to use fresh, dried beans. Follow the directions on the package.)
Dice the roasted red pepper and tomato to a size that suits you.
Mix all ingredients thoroughly.
Chill for an hour (or more) to allow all the flavors to marry.