Peel the cucumber and then cut into half vertically. Use a spoon with a sharp point, like grapefruit spoon for example, to scoop off the seeds. Regular spoon will work too, so don't sweat it if you don't have grapefruit spoon. It just makes the work a little easier
Cut the cucumber into cubes or you can cut it into half-circle shape. It doesn't matter. I prefer the cube shapes
Place the hot water and sugar in a glass-jar. Stir to dissolve the sugar. Add the vinegar and chili. Add the cucumber. Close the lid of the jar and shake it. You can pickle this in a non-reactive bowl too. Whatever works for you. Let it pickle for at least 1 hour in a refrigerator. I love it chilled because it's just so refreshing. You can store this in the refrigerator for up to 1 week