Place beef, 2 tsp Mediterranean spice, 2 TBSP feta cheese, and 1/2 tsp hot sauce in a large bowl (save the rest of the spice, feta, and hot sauce for later). Season with salt and pepper. Mix until combined. Shape into two 1/2-inch-thick patties and set aside.

Wash and dry all produce. Zest lemon, then cut into quarters. Halve, peel, and thinly slice shallot. Heat a grill over direct heat and brush grates with 2 tsp oil. TIP: If cooking indoors, heat a drizzle of oil and 1 TBSP butter in a grill pan or large pan over medium-high heat.

Add patties to grill or pan and cook until marks appear on bottom, 7-8 minutes. Flip and cook until marks appear on other side, 6-7 minutes more. Transfer to a plate. Meanwhile, mix together sour cream, a drizzle of olive oil, remaining Mediterranean spice blend, and remaining feta cheese in a small bowl. Set aside.

Trim cucumber ends, then quarter lengthwise. Cut crosswise into 1/2-inch pieces. Quarter tomatoes, then dice into 1/2-inch pieces. In a medium bowl, toss together cucumbers, tomatoes, half the shallot (add more for extra onion-y flavor), lemon zest, juice from two lemon quarters, 1 tsp mustard (we sent more), a large drizzle olive oil, and 1 tsp sugar. Season with salt and pepper.

Microwave 1 TBSP butter in a small, microwave-safe bowl until melted, about 20 seconds. Split buns in half and brush cut sides with melted butter. Place on grill or in pan used for burgers cut-side down and toast until light golden, 1-2 minutes.

Spread sour cream mixture onto bottom halves of buns, then place patties on top. Top with remaining bun halves. Sprinkle over remaining hot sauce, if desired. Divide between plates. Serve with salad and remaining lemon on the side. TIP: Put a little salad inside your burger for a cool, crisp sensation.