Cook the red lentils (If you already have leftover cooked lentils prepared, skip to step 2) following the directions here.
Meanwhile, heat up the 1 teaspoon of oil in a saucepan or skillet on medium heat. Once the oil is hot, sauté the onions in the oil for a minute, then add the mushrooms and cook for about 5 minutes.
When the lentils are cooked, drain and measure out 2 cups of cooked lentils. Add the seasonings (cumin, garlic powder, salt and pepper) to this drained amount. Stir to mix in the seasonings.
Using a wooden spatula, move the chopped mushrooms and onions mixture to the side of the saucepan and pour the remaining teaspoon of oil on the empty side of the saucepan. Add the minced garlic and sauté for about 1-2 minutes or until the garlic turns golden.
Add the chopped tomatoes and the dried or fresh basil to the garlic and stir quickly, cooking for 1-2 minutes until the tomato pieces soften.
Add the seasoned cooked lentils to the tomato mixture, and stir to combine. Cook for another 2-3 minutes to heat up the lentils.
Combine the lentil tomato mixture with the mushrooms and onions. Stir all together. Once heated through, add the chopped spinach leaves (optional). Stir and cook for another 2 minutes until the spinach leaves are just wilted. Taste and adjust seasonings (you may add a bit more salt and pepper if you desire!). Serve warm.
If you do not want to use mushrooms, you can substitute the 2 cups of chopped mushrooms in this recipe with either 2 cups of chopped colored bell peppers, or a combination of one cup of chopped bell peppers and slightly more chopped raw spinach or baby kale/spinach leaves.
For an oil-free recipe, substitute the oil used in this recipe with 2-4 tablespoons of vegetable broth (heated up well first in the saucepan) to sauté the onions and chopped mushrooms (or chopped bell peppers), then another 2 tablespoons of vegetable broth later in this recipe to sauté the garlic and diced tomato pieces. If at any point the vegetable broth gets cooked off and the saucepan contents are looking too dry, you can turn down the heat setting on the stove slightly and add in 1-2 more tablespoons of vegetable broth into the saucepan then continue the cooking process.