The visitors took a three-goal lead before half-time, with Matthew Hoppe, Pharrell Willis and Sonny Finch scoring for the Teessiders.
Substitute Joe Gibson then added a fourth before Michael Spellman pulled a goal back for the young Black Cats soon after the interval.
The match was then more reminiscent of a basketball match as Hoppe and Finch both scored again for Boro, either side of a goal from Sunderland substitute Caden Kelly.
Another Black Cats substitute Ethan Moore then made it 6-3, before Jack Stott added a seventh for Boro.
In stoppage-time, Kelly netted his second, while Ellis Taylor also got on the scoresheet.
Here’s how each Sunderland player fared:
1. Jacob Carney - 4
Often left exposed but was beaten too easily for some of the goals as Middlesbrough scored seven. 4 Photo: Frank Reid
2. Callum Wilson - 4
Was regularly exposed at right-back with most of Boro’s goals coming down that flank. 4 Photo: National World
3. Ben Crompton - 4
Conceded possession for Boro’s first goal and often looked lost in Sunderland’s backline as the visitors ran riot in the second half. 4 Photo: FRANK REID
4. Nathan Newall - 4
Played as a centre-back and endured a rough second half as he was regularly beaten. 4 Photo: Frank Reid