Rule reminder
'Come' (how/as) followed by the indicative describes a real, factual manner. 'Come se' followed by the subjunctive describes an unreal, imagined, or hypothetical manner. The tense after 'come se' is always subjunctive (imperfetto or trapassato). The tense after 'come' alone is indicative.
Faccio ___ mi hai insegnato — metto sempre lo zucchero alla fine.