Sauté onion and garlic in olive oil in a large skillet until tender. Add chopped peppers; simmer, uncovered, 5 minutes, stirring frequently. Add tomato and salt; simmer an additional 10 minutes, stirring occasionally.
Ladle relish into hot sterilized jars. Cover with metal lids, and screw bands tight. Store in refrigerator. Serve with tortilla chips.