Tosefta על חלה 3:11

Vegetables of chullin that are cooked in untithed oil, behold, this is forbidden in any amount. If he has a supply in another place, he can take it out according to the precise amount (Hallah 3:8), and if not, [as to] something that [can be] mixed in [with oil], he mixes it and takes [the precise amount], and [as to] something that cannot be mixed [with oil], he takes from that [very] stalk or cut or egg.