Shayon Harrison grabbed all three of our goals, the striker putting us 2-0 up before George Honeyman pulled one back for the visitors.
Harrison completed his treble with a fine left-footed finish in stoppage time.
Spurs U21s: Glover, Walker-Peters, Lesniak, Walkes, Georgiou (Maghoma 90), Stylianides, Winks, Miller, Goddard (J Pritchard 69), Sonupe (Marsh 82), Harrison. Substitutes (not used): Roles, McDermott (GK).
Sunderland U21s: Stryjek, J Robson (Nelson 85), T Robson, Agnew (c), Brady, Beadling, Lawson, Smith (Wright 75), Mandron, Honeyman, Greenwood. Substitutes (not used): Molyneux, Ledger, Talbot (GK).