A misunderstanding arising from the peculiar procedures of the Friday breakfast, the most exalted foreign policy decisionmaking forum of the Carter administration, was in large measure to blame for the embarrassing U.S. flip-flop on Middle East policy at the United Nations, according to informed official sources.

The sources said the basic decision to cast a U.S. vote for a resolution criticizing Israel was made at the regular weekly breakfast of President Carter and his senior foreign policy advisers a week ago today.

Secretary of State Cyrus R. Vance is reported to have left the breakfast believing that one of Carter's conditions for U.S. approval of the resolution was deletion of a particular section, paragraph 7, which criticized Israeli legal procedures in East Jerusalem.

But Carter, according to administration accounts, believed that all references to Jerusalem, not simply the offending paragraph 7, would be deleted from the resolution as a price of U.S. support.

Disagreements and misunderstandings about what has been agreed on at the breakfasts are possible because, throughout the Carter administration, no centrally approved minutes have been kept of this most important forum for presidential decisions.

In the absence of formal minutes, which would be circulated to those involved and become the basis for further discussion or official action, each of the Cabinet-level participants dictates his recollection of morning'ss talk and decisions. Thus there is room for disagreement between the recollections of the different members of Carter's high policy council, and between some of those members and the president.

There has been criticism of this procedure for many months among middle-level administration officials, particularly because the Friday breakfast has been the forum for "pet project" items to be taken up outside normal channels due to their sensitivity.In such cases, the chances of imprecise decisions and conflicting understandings are greater than usual.

There is no evidence that top-level attention was ever given to the need for an agreed set of minutes, despite the fact that more and more high policy questions have been decided at this informal and exclusive forum, where only top officials are in attendance.

The attendance list at last Friday's meeting, for example, included Carter, Vance, Secretary of Defense Harold Brown, presidential assistant Zbigniew Brzekinski, White House chief of staff Hamilton Jordan and presidential adviser Hedley Donovan.

In addition to the misunderstanding arising from conflicting recollections and interpretations of last Friday's discussion, there is little doubt that the intense but predictable reactions from Israel and the American Jews community played a major role in the awkward and abrupt reversal.

The details of the administration's flip-flop are scheduled to be explored next week by the Senate Foreign Relations Committee, which has asked Vance, Assistance Secretary of State Harold H. Saunders and U.N. Ambassador Donald F. McHenry to testify Thursday.

Sen. Richard Stone (D-Fla.), who will chair the hearing in the absence of Chairman Frank Church (D-Idaho), said yesterday he has asked for internal documents on the decision, including cables of instruction to McHenry.

Stone said the committee hopes to find out what happened, what U.S. policy is regarding the issues involved, and what future policy will be.

He said that more than one day of hearings may be necessary, but that no investigators have been assigned to the case. "I think the administration will tell us exactly what happened" Stone said.

Sen. Jacob K. Javits (R-N.Y.), ranking minority member on the committee, expressed skepticism that Vance was the one at fault in the policy reversal, although Vance publicly accepted responsibility.

Without expressing a view of what had happened, Javits said the incident showed "anarchic management or lack of judgment almost beyond understanding."