What food is quick to make and tasty to eat?

You can cook fish and rice in the microwave.

I'll speak to the ease rather than the speed of preparations.

In that regard I like Crock Pot and Instant Pot. Both of them can cook just about anything, including cakes. The best thing about them is you can just dump everything in them and forget until ready. I believe Instant Pot is a bit more versatile and stuff like rice and hard boiled eggs come out perfect every time. Youtube has neverending parade of recipes and demos (of any level of complexity) for both Crock/Instant Pot. To save more time one can also invest in food processor (chops up your veggies and whatever in no time) and countertop dishwasher.

My wife has brought fish into my go-to selection. She bakes or pan-sears salmon or tuna. Probably the highest combo for speed and tasty. Not optimized for cost obviously.

salt+pepper+olive oil+lemon juice, fish on parchment paper in a cast iron pan, bake for 10-15 minutes or until flaky, depending on fish mass

active time - 1 minute?

https://www.allrecipes.com/recipes/1884/main-dish/sandwiches...

Smoothies and sandwiches :)