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.