Adjust the heat: For a milder aji, remove the seeds and membranes from the jalapeño before chopping. For extra heat, leave them in or add a second jalapeño. Freshness is key: Use the freshest ingredients possible for the most vibrant flavor. Look for bright green cilantro and firm, ripe tomatoes. Storage: Aji can be stored in an airtight container in the refrigerator for up to 3 days. The flavors will continue to develop over time. Variations: Feel free to experiment with other ingredients such as bell peppers, or different types of chili peppers to customize your aji.