If not already prepared, cook lentils. Follow directions on the package. Avoid overcooking the lentils and take off the stove when they're cooked, but not mushy. Drain.
Place walnuts on a baking sheet and toast for 2-4 minutes, until fragrant. Watch closely to avoid burning.
In a small pan on the stove. Heat 1 teaspoon of oil or add cooking spray to the pan and heat to medium. Add jalapeno peppers and saute for 1-2 minutes. Add minced garlic. Saute for 30 seconds until garlic is fragrant and remove from heat.
Place black beans, walnuts, and lentils in a medium-sized mixing bowl. Combine with a fork, mashing together only slightly. You want to keep texture in the mixture and avoid over-mashing it into a "mush".
Add jalapeno garlic mixture, pineapple, and green onions to the mixing bowl. Stir gently to combine.
Spread ¼ cup of enchilada sauce on the bottom of the pan. Lay a tortilla down in the pan ontop of the sauce. Then begin to layer: ¾ cup filling, tortilla, then ½-3/4 cup sauce. Repeat until all ingerdients have been used and you have 3 layers of filling. End with sauce on top of a tortilla.
Bake at 375°F for approx 45 minutes. If the top starts to brown too quickly, cover with tin foil.
Avoid overcooking the lentils and over-mashing when combining the ingredients. You want the texture to be crumbly, not paste-like.*All nutrition information is an estimate based on ingredients used.