Do you understand how bitmaps and raster drawing works? Everything is represented as a 2d array of pixels. The circle selection before you paint can be moved/scaled/etc and then when you actually want to draw the circle trace the path with the appropriate thickness and use antialiasing if you need to smooth it.
If you want to make vector drawings, take a look at InkScape. GIMP is the wrong tool for that, so use the right tool for the job if that’s what you want to do.
What’s the problem with making a circle with the select tool and then tracing it or filling it? It’s not hard to make a circle in GIMP…
I’d break up the queso fresco, grind some salt to a powder with a mortar and pestle, add it to the queso fresco and mix together, then put the ball back in some cheese cloth and re-press it. You could probably add a sprinkle of water before putting it in the cloth to help the texture if it’s too crumbly. Queso fresco needs to be salty, otherwise it’s just like dry ricotta.
Just peeled, rinsed, tossed in olive oil with an oodle of salt and some paprika, and cooked in the oven.
And corn. The little sweet bursts of the corn just adds a whole dimension of delicious to a chili.
You could also use the select tool to draw a single circle, then go to the Select menu and click Border which will create the outer and inner selections with the width you specified between them. Much easier than selecting a circle and de-selecting the centre hole.