Prepare the Tomatoes: Chop your cherry tomatoes in half, keeping sizes consistent for even cooking.
Sauté the Onion: In a skillet, heat olive oil on medium heat and sauté the red onion until soft.
Add the Ingredients: Add cherry tomatoes, jalapeño, sherry vinegar, and sugar to the skillet.
Cook the Mixture: Stir the mixture occasionally, letting it simmer for about 20 minutes until it thickens.
Season and Serve: Add salt to taste and serve warm or cold as per your preference.