Activate the sauté mode on your Instant Pot and pour in the oil if using; sauté the chopped onion for about 2 to 3 minutes until it softens, stirring often; if skipping oil, add water to prevent sticking.
Next, toss in the chopped carrots and minced garlic, cooking briefly for 30 seconds while stirring constantly to avoid burning the garlic; mix in the smoked paprika, crushed red pepper flakes, and cayenne pepper, then stop the sauté function.
Add your bouillon powder, canned tomatoes with liquids, water, lentils, chopped cabbage, sea salt, and black pepper into the pot; stir thoroughly to combine and press the cabbage gently to keep everything submerged and below the fill line.
Close and lock the lid, ensuring the valve is sealed, then set the Instant Pot to cook at high pressure for 10 minutes; it will take about 20 minutes to pressurize before counting down.
Once cooking is finished, carefully perform a quick release by turning the valve to vent to release steam, which can take around 10 minutes given the volume.
After the pressure indicator drops, open the lid with care and stir in the soy sauce or tamari, liquid smoke if you want it, vinegar, and vegan butter if using.
Let the soup rest for a few minutes to cool slightly, then taste and add any extra seasoning if needed before serving.
