die Portion
portion
A specific amount of food intended for one person or served to one person.
Ich hätte gern eine große Portion Pommes frites.
I'd like a large portion of French fries.

portion
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portion
A specific amount of food intended for one person or served to one person.
Ich hätte gern eine große Portion Pommes frites.
I'd like a large portion of French fries.

When 'Portion' (portion) is followed by a noun that describes the type of portion, this noun usually comes directly after it without a preposition. Using 'von' (of) is grammatically correct, but less common in everyday language.
Er bestellte eine Portion Nudeln mit Tomatensoße.
He ordered a portion of pasta with tomato sauce.
In connection with food, 'Portion' (portion) is often used with the adjectives 'groß' (large), 'klein' (small), or 'doppelt' (double). Typical verbs are 'bestellen' (to order), 'nehmen' (to take), or 'bekommen' (to get).
Eine kleine Portion Pommes, bitte!
A small portion of fries, please!
In the figurative meaning, 'Portion' (portion) is often combined with abstract nouns. Typical phrases are 'eine Portion Glück' (a portion of luck), 'eine Portion Mut' (a portion of courage), or 'eine extra Portion Geduld' (an extra portion of patience).
Mit einer ordentlichen Portion Selbstvertrauen schaffst du die Prüfung.
With a solid portion of self-confidence, you'll pass the exam.
part
'der Teil' and 'die Portion' can both mean a share of something larger. 'Teil' is general and describes a piece or section. 'Portion' means a specific amount, especially of food, often for one person. It can also be used for other quantities. Learners may confuse the words when something is divided up. If you mean the structure or a piece, use 'Teil'. If you mean an amount that someone receives or uses up, 'Portion' fits better.

Zum Mittagessen nimmt er eine kleine Portion Reis.
For lunch, he takes a small portion of rice.
Wegen des Regens ist ein Teil des Festes ausgefallen.
Because of the rain, part of the festival was canceled.