$50 monthly shop

I’m 17 and I need recipe ideas that are super cheap.

For example my breakfast is 20g oats, 1/4 cup milk, 1/2 cup water, 1tbsp cocoa powder and 1tsp of sugar. Sometimes a banana.

Lunch is a piece of bread with mayonnaise and cumin, or an apple (only at the start of month because they expire)

I can only shop once a month so freezeable/dry items are preferable.

I have a multi and iron supplements so that shouldn’t be a concern.

I’m aiming for at least 800 calories.

I am planning to make sweet potato soup for dinners too. Filling and cheap.