Place onion, jalapeno, and bell pepper in food processor.
Pulse until vegetables are chopped. Add peaches and pulse until incorporated.
Pour ingredients into large bowl. Mix in tomatoes, lemon juice, sugar, vinegar, spices, and cilantro (if using). Stir to incorporate.
Refrigerate for at least 1 hour before eating.
Notes
This is also amazing with fresh peaches and tomatoes! Swap 3-4 large, peeled peaches for the canned peaches and 3-4 large tomatoes, for the crushed and canned tomatoes.