What condiment is commonly an optional choice on Grilled Veggies?

Mustard is commonly an optional choice on grilled veggies due to its tangy flavor that can complement and enhance the natural taste of vegetables. It adds a layer of zest and can work well in various preparations, particularly when grilled vegetables are served in sandwiches, bowls, or as a side dish. Its versatility and ability to pair well with both warm and cold dishes make it a popular condiment choice.

In contrast, while mayo can be used with grilled vegetables, it is not as typical compared to mustard, which tends to be a more favored option in casual dining scenarios. Oil and vinegar are often used as dressings rather than directly as condiments on the veggies themselves. The choice of "None" would imply that no condiment is served, which overlooks the common practices of flavoring grilled veggies. Thus, mustard stands out as a recognizable and popular optional condiment for this dish.