I'm afraid I don't... fully get this.

GoodFarsight said:

I'm afraid I don't... fully get this.

Mako's parents were deceased before the series starts. It seems that the meal being served reminds both Mako and her grandmother of them, which is why they are tearing up. This is clued in by a sparkle on the double photographs in the upper left along with a bowl used for burning incense for the deceased.

GoodFarsight said:

I'm afraid I don't... fully get this.

You could also interpret as Mako and her grandma, being incredibly lazy people are just overjoyed by the fact that they don't have to put in any effort to cook for themselves