Mujaddara with Tzatziki

Name: Mujaddara with Tzatziki
Cuisine: European, Middle Eastern, Asian, Greek, Mediterranean
Ingredients: 1 Tbsp + 1 tsp olive oil, divided; 1¼ cups/200g thinly sliced onion; 12 oz/340g cauliflower rice; 1½ cups/360ml water; ⅓ cup/60g green or brown lentils; 1 large clove garlic, minced; 2 tsp roasted ground cumin (see Cooking Notes); 1 bay leaf; 1 tsp fine sea salt; ½ tsp cracked black pepper; 1 Tbsp finely chopped fresh Italian parsley; 1 medium cucumber (7 oz/200g), grated; ½ tsp fine sea salt, plus more for salting cucumber; 1 cup/220g whole-milk plain Greek yogurt; 1 Tbsp finely chopped fresh dill or mint; 1 Tbsp lemon juice; 1 tsp olive oil; ¼ tsp cracked black pepper