Wash and dry all produce. Adjust rack to upper position and preheat oven to 450 degrees. Halve, peel, and finely dice onion. Mince garlic. Halve lemon. Melt 1 TBSP butter in a medium pot over medium-high heat. Add onion and half the garlic. Cook, stirring often, until softened, about 5 minutes.

Season onion with salt and pepper, then stir tomatoes, 11/2 cups water, and stock concentrate into pot. Bring to a boil, then lower heat and reduce to a simmer. Cook until thickened, 8-10 minutes. Meanwhile, place 1 TBSP butter and remaining garlic in a small, microwave-safe bowl. Heat in microwave until melted, about 30 seconds.

Place naans on a lightly oiled baking sheet. Brush or drizzle all over with garlic butter. Season with salt and pepper. Bake in oven until lightly toasted, 4-5 minutes. Sprinkle naans with mozzarella, then return sheet to oven and continue baking until naans are crisp and mozzarella melts, about 3 minutes more.

Once soup is thickened, set aside off heat and let cool slightly. Season generously with salt and pepper. Stir in 1 tsp sugar, half the sour cream, and a pinch of chili flakes (to taste). Taste and season again with salt and pepper. TIP: If soup tastes sharp, add another 1/2 tsp sugar.

Place lettuce, sunflower seeds, 1 TBSP olive oil, and a squeeze or two of lemon (to taste) in a medium bowl. Toss to combine. Season with salt and pepper.

Cut naans in half. Divide soup between bowls and dollop with remaining sour cream. Sprinkle with a pinch of chili flakes (to taste). Serve soup with naans and salad to the side. TIP: Dunk the naans into the soup to get the best of both worlds.