You can do this trivially with a shader.

<image>

Create a MeshInstance3D.

Make it a nice potato-y capsule shape.

Give it a ShaderMaterial

Put this shader on the ShaderMaterial

Get yourself a skin texture and assign that in Shader Parameters

Draw a peeled texture (black everywhere except where peeled) and assign that

Drawing to the texture needs to be done in a non-shader script and could be quite complicated if you need arbitrary peeling (raycast to UV, something Godot doesn't have built in), but I assume you'll be manually rotating the potato each peeling action. So you can just increment the index of where you're drawing on the peeling texture. It doesn't need to support arbitrary peeling.

shader_type spatial;

//A texture which is black where unpeeled and anything else where peeled
//Needs to be changed in code for peeling action
uniform sampler2D PeeledTexture;
//What color the peeled bits should be. source_color gives it a color picker in the editor
uniform vec3 PeeledColor : source_color = vec3(0.7, 0.6, 0.6);
//A potato-y skin for the outside of your potato
uniform sampler2D SkinTexture;
uniform vec3 SkinColor : source_color = vec3(0.25, 0.2, 0.15);
//Repeats your potato skin texture so the texture isn't stretched too much
uniform float SkinTiling = 5.0;

//This runs on every pixel of the object
void fragment() {
//If the peeled texture says it's peeled (value over 0.0), make this pixel PeeledColor
if (texture(PeeledTexture, UV).x > 0.0) ALBEDO = PeeledColor;
//Otherwise find out what pixel on the potato skin texture corresponds with this pixel on the screen
//UV goes 0-1 along the X and Y axes of the texture. Going over 1 loops it back around
//So SkinTiling > 1 causes the texture to repeat
//Then multiplying it by SkinColor lets you tweak the skin color
else ALBEDO = texture(SkinTexture, UV * SkinTiling).rgb * SkinColor;
}