A common substitute for Mexican crema is a mixture of sour cream and heavy cream or even Greek yogurt. You can blend equal parts sour cream and heavy cream until smooth to achieve a texture similar to Mexican crema. Alternatively, you can use plain yogurt or crème fraîche as substitutes, though they may have slightly different flavors and consistencies compared to Mexican crema. For a dairy-free alternative, you can use raw cashews blended with a bit of lime juice and salt to mimic the tanginess of crema.