1. Dice kielbasa. In a large pressure cooker (lid off), fry kielbasa with a bit of vegetable oil.
2. Meanwhile, dice onion and mince garlic. Add to pot, cooking until onions are soft.
3. Stir in lentils, frozen vegetables, canned tomatoes, bay leaf, and thyme.
4. Reduce heat and cook until lentils have darkened (~9 minutes). By “sweating” the lentils in acid, they stay firm and don’t get mushy.
5. Add chicken broth and water, seal the pressure cooker, and cook with medium or high pressure for ~10 minutes.
6. Cool enough to remove the lid safely, stir in spinach and fresh tomato.