Im not too worried about Serotonin Syndrome because Remeron is a TCA not an SSRI
TCA usually refers to "tricyclic antidepressants", which should not be confused with "tetracyclic antidepressants" (TeCA's), which is what mirtazapine is.
Tricyclic antidepressants essentially combine features of atypical antipsychotics (blockade of 5HT2x, adrenergic and histaminergic receptors) with those of SNRI's (inhibition of the serotonin and noradrenaline transporters). As such, those are perfectly capable of giving you serotonin syndrome, if their anticholinergic effects don't kill you first.
Mirtazapine, on the other hand, does not inhibit the serotonin and noradrenaline transporters to any relevant extent (the other two tetracyclic antidepressants do inhibit NET, but likewise lack affinity for the serotonin transporter). However, by blocking alpha-2 adrenergic and 5HT2c serotonergic receptors (which normally limit the release of monoamine neurotransmitters in certain regions of the brain), they boost neurotransmitter levels in an indirect fashion, which seems to be far less prone to causing dangerous reactions when overdosed. The technical term for this pharmacological mode of action is "NaSSA", "Noradrenergic and Specific Serotonergic Antidepressant". Tetracyclics also generally have much weaker anticholinergic effects than tricyclics, contributing to their favorable safety profile.
Anyway... I seriously doubt a little bit of turmeric and black pepper is going to be enough to potentiate mirtazapine to any major degree. Be aware though that if you don't have any cross-tolerance from other meds, it is perfectly normal for the H1 antihistaminergic effect to hit you like a truck for the first few days.