A very common type of pudding is a pudding made from liquid thickened with starch. It is usually made with milk, but you can use other liquids as you see fit. Fruit juice will probably work best. For starch, use plain potato, corn or wheat starch. The "absolutely no fat" condition is very detrimental to the taste. A trick to make it taste richer would be to include some whey powder. Any sweetener will work - sugar, baking sweeteners like honey or agave syrup, or artificial sweeteners (keep in mind the max temp for artificials). You can enhance the flavor wit the usual suspects - vanila, cinnamon and other spices - and/or serve with syrup poured over. Adding food coloring is also a good option, as it affects the perceived taste too.
To prepare the pudding, use a base ratio of 1 part starch to 10 parts liquid (you can change that later, depending on your preference for firmness). Mix the dry ingredients (sugar, cinnamon) with the starch in a small bowl. Stir in some cold liquid, around 1 tbsp per 25g starch, until you have a slurry. Bring the remaining liquid to a boil. Remove from the heat and quickly stir in the slurry. Return to the (reduced) heat and let simmer for some minutes, stirring contantly. Stir in the liquid ingredients (e. g. honey, molten caramel). Pour into the form(s) and leave it to cool, at best overnight. It will set and should be firm enough to slice. Alternatively, it can be eaten warm (and still soft) from bowls.
You mention Jello. I don't consider gelatine jellies to be a "pudding", but maybe this is a language problem on my part. You can make a gelatine "pudding" with powdered gelatine, just follow the instructions on the package. Gelatine itself is pure protein and does not contain fat.
It is also possible to use modern thickening agents to thicken a juice or another liquid to a more or less pudding-like consistency, but this is unusual in home cooking. If you are interested, look up guar gum or xanthan gum. There is a free e-book oh hydrocolloids often linked here on SA, but it probably goes much beyond what you need. Still, you can search for it if interested.
I think it all got too hot, but there might be other problems.
- Did you mix the cornstarch in completely? Leaving undissolved cornstarch is a sure way to obtain 'blobs'.
- Did you pour the hot milk onto the egg-mixture? You should do that very slowly and whisk vigorously (while trying to splash everything). If the eggs get too hot, they will coagulate.
- Did you use a double boiler? Putting the pan on an open flame will make the bottom too hot and the eggs will coagulate.
- Even if you did use a double boiler, did you whisk regularly while heating? The eggs at the bottom will become far warmer than the eggs in the center...
As rumtscho mentioned, a thermometer will be useful for monitoring the done-ness of the custard.
Generally, a fully cooked custard should not exceed 80 °C; it begins setting at 70 °C.
Source: Wikipedia
Best Answer
Puddings, of the type in your recipe, are thickened mostly by starch gelling. The egg yolks and milk provide some thickening as well as the smooth, custardy texture.
Both the starch and egg proteins gel before the boiling temperature. Recipes call for a few minutes of boiling for an entirely different and fascinating reason.
There is an enzyme in raw egg yolks that digests starches. A few minutes of boiling is required to deactivate those enzymes. If your pudding didn't gel, and some time has passed, your eggs may have eaten your cornstarch. In this case, boiling it more wouldn't help.
You might try whisking in some more starch and then boiling it again. This would take some experimentation. I wouldn't replace the entire quantity of starch from the recipe at first.