You can add some baking soda to the original recipe (1/2 c. juice or slightly less). Baking soda is alkaline (or a base if you're a chemist). It will neutralize the acid (source of tartness sensation). THOROUGHLY stir in less than 1/8 teaspoon at a time until the tartness is reduced to the level you wish. Be careful as too much will remove all the tartness and therefore the taste sensation the lime juice adds.
This seems like a fun adventure. I'll say upfront that I've never tried what I'm about to suggest.
When I read your question title the first thing that came to mind is a Puerto Rican sandwich that is very popular in Chicago, the jibarito. It's a sandwich in which the bread has been replaced by flattened and fried plantains. I think doing something similar could yield nice results for a pie crust. You just press the peeled plantains between two cutting boards to get your desired thickness.
As far as not frying, you should also be aware that fried plantains are damn good. I've never eaten a plantain that wasn't fried. That said, if you are committed to not frying I have suggestions as well.
First, the boiling and mashing is right out. I don't think the processing you'll be doing will result in a crust that holds up at all.
Roasting, or better yet, pan frying in butter I think is the way to go. I suggest just greasing a large frying pan with butter and pan-frying the plantain over medium-low heat until done.
If pan-frying is not your thing either, I'd suggest just brushing them with melted butter and tossing in a 400 F (200 C) oven for 10-15 minutes (complete SWAG - never oven roasted plantain). With either the roasting or pan-frying method you may wish to sprinkle each buttered side with a little sugar to add a little sweetness and a nice carmelization.
Best Answer
Oil is not substituted for eggs, as it has completely different properties. It is normally substituted for the solid fat.
While it is certainly possible to do it this way, it is much fussier than just using solid fat. It requires frequent trips to the refrigerator during making if you want to end up with a solid crust and not just a pap. You have to be well experienced with pie doughs to be able to recognize exactly when to put it into the refrigerator or freezer. The result is not all that different for solid fact, except for 1) taste, if you use some strongly flavored oil (like one of the toasted nut oils), and 2) bragging rights that you pulled it off.
If you are just looking for an easy recipe, use one with solid fat (butter, lard or shortening; shortening is easiest to work with but has the least taste) and adhere to the instructions. You will recognize a good pie crust recipe by following criteria: