Start with fresh or canned corn; if using fresh, cook it briefly to enhance the flavor.
Dice the red and green bell peppers into small pieces.
Finely chop the red onion and cilantro.
If using, seed and mince the jalapeño.
Combine corn, bell peppers, onion, cilantro, and jalapeño in a large mixing bowl.
Squeeze the lime juice over the mixture.
Sprinkle salt, pepper, and cumin (if using) to taste.
Gently mix all ingredients until well combined.
Let the salsa sit for about 10 minutes to allow flavors to meld.
Serve with tortilla chips or use as a topping for tacos or grilled chicken.