Mexican Crema
Mexican Crema is a cultured dairy ingredient used for tang, richness, and body. Add it gently, avoid harsh boiling, and taste before adjusting salt or acid.
Identity
Cultured dairy
Add gently and avoid harsh boiling.
Cultured dairy adds tang, richness, and body. Stir it in gently, avoid prolonged hard boiling, and taste before adding more acid or salt.
Wikimedia Commons
Reference image
Mexican Crema reference image.

Source: Wikimedia Commons
Substitutions
Acceptable
Sour Cream -> Mexican Crema
1/4 cup (60ml) sour cream or Mexican crema
The source lists this as an alternative in the same ingredient row.