Sociedad ends 32-year wait for Copa final
The two-time Copa winner has been in outstanding form in recent weeks, climbing to sixth in LaLiga, and a sixth straight win in all competitions ended a 32-year wait to return the showpiece.
La Real will now face either Granada or Athletic Bilbao , with Sociedad's Basque rival 1-0 up - next month after building on a narrow home lead against second-tier Mirandes.
Imanol Alguacil's side still did not quite hit the heights of their stunning quarter-final triumph at Real Madrid, but inspirational captain Mikel Oyarzabal tucked away his second penalty of the tie four minutes before half-time, and Mirandes could not recover.
Nacho Monreal hung up an early cross and Adnan Januzaj directed a towering header from it just wide, but the game's next effort of note did not follow until Limones parried clear Willian Jose's powerful 20-yard drive with 26 minutes on the clock.
That attempt came amid an improved spell from the visitors, and they had their breakthrough before the break after Mickael Malsa blocked Joseba Zaldua's cross with his arm.
Skipper Oyarzabal kept his nerve from 12 yards, sending Limones the wrong way to stretch La Real's aggregate lead and cancel out their opponents' away goal.
Januzaj went agonisingly close to a second shortly after the restart, but his swirling strike from wide on the right crashed away off the crossbar after beating Limones.
Chances were scarce at the other end, however, and Alex Remiro pounced on Matheus Aias' tame close-range header as Sociedad eased to victory, with a stoppage-time second from substitute Alexander Isak disallowed for offside.