When formulating a dry taco seasoning blend, what additional ingredient should be added if the key seasonings weigh 5 grams?

When creating a dry taco seasoning blend, the purpose of adding an ingredient like starch is primarily to act as a bulking agent. In this context, the key seasonings weigh 5 grams, and adding starch can help to increase the volume of the mix, ensuring that the flavor is well-distributed throughout the blend.

Starch not only serves to bulk up the mixture but can also aid in the ease of packaging and measuring, as it helps maintain the texture of the seasoning. It can absorb moisture, which is particularly useful in dry seasoning mixes, as it keeps them free-flowing and prevents clumping. This characteristic is important in culinary applications where an even distribution of flavors is desired.

While other ingredients like salt might enhance flavor, they do not serve the same purpose of bulking and improving the mix's practical handling characteristics. Silicon dioxide might help with anti-caking, but it does not contribute directly to the flavor profile or bulk of the seasoning. Soy oil, although it can coat spices, is not suitable for a dry blend since it would introduce moisture. Thus, the most appropriate ingredient to combine with the key seasonings in this scenario is starch.