spinach and potato soup

Name: spinach and potato soup
Ingredients: 1 teaspoon olive oil; 3/4 cup yellow onion, chopped (about 1 med onion); 3 garlic cloves, minced; 1 teaspoon basil or thyme, dried; 1 teaspoon salt or to taste; 1.25 cups potato, peeled and chopped (about 1 medium size potato); 4 cups water; 1 teaspoon red chili flakes or to taste; 4 cups fresh spinach leaves, washed; 3 teaspoons lemon juice or to taste; 5 tablespoons fresh feta cheese, crumbled