Start by placing the bacon bits in a cold, medium-sized saucepan and frying them over medium-high heat until they are crispy.
Transfer it into a plate lined with kitchen paper --- to absorb excess oil, then set aside.
Using the same pan (and the bacon oil), saute the garlic and onion until they soften.
Add the flour, mix constantly, and cook until it turns brown --- lower the heat to avoid burning the flour.
Pour the stock, cover with a lid, adjust the heat back to medium-high, and bring to a boil.
Add the drained green lentils, cover, lower the heat, and simmer until they soften.
Add the chopped potato and carrot, and continue simmering until tender.
Add half a teaspoon of vinegar, the spinach, and the bacon from earlier.
Mix, taste, and adjust seasoning by adding salt, ground black pepper, and more vinegar.
Put the lid back, turn the heat off, and let it sit for a few more minutes.
Transfer to bowls and garnish with more bacon, if preferred --- serve!