Recipe calls for a heaping teaspoon of a liquid ingredient
Obviously you can't "heap" a liquid.

What helps is if you remember that in cooking measurements are not set in stone. The amount given in a recipe can basically always be tweaked to your liking - a tablespoon need not be the "perfect" amount, but should be a good starting point. E.g. the siracha: some like their dish hotter, some less so.

In your case I'd interpret "heaping" as "generous" or "a bit more than". (The opposite of "scant", where you'd fill the spoon not quite full.) 

I'd start with a spoonful and add more to taste, if necessary.