Albert Barnes Commentary Leviticus 6:20

"This is the oblation of Aaron and of his sons, which they shall offer unto Jehovah in the day when he is anointed: the tenth part of an ephah of fine flour for a meal-offering perpetually, half of it in the morning, and half thereof in the evening." — Leviticus 6:20 (ASV)

See Leviticus 4:3. Aaron’s sons here spoken of must be the succession of high priests who succeeded him. The day of this offering was probably the eighth day of the ceremony of consecration (Leviticus 8:35; Leviticus 9:1), when the high priest appears to have entered upon the duties of his office.

A meat offering perpetual - Jewish tradition is in favor of these words implying that this מנחה mı̂nchāh was offered by the high priest as a daily rite from the time of his consecration.