Step 1

Preheat oven to 400º. Peel and trim ends off 1½ lb. mixed onions. Cut in half lengthwise. Place halves cut side down on cutting board, then thinly slice.

Step 2

Line a rimmed baking sheet with parchment paper. Toss onion and 4 garlic cloves with ¼ cup oil and 2 Tbsp. water until evenly coated. Season with salt and toss again until well coated. Mound onions and garlic in center of sheet pan rather than spreading them out; this allows them to steam and soften without browning too quickly.

Step 3

Bake, tossing and stirring onions every 10 minutes, until all onions are golden brown and softened, 40–50 minutes total (some onions will brown more than others but that’s okay!). Let cool.

Step 4

Transfer onions and garlic to a cutting board and squeeze out garlic cloves from peel. Using the flat side of a chef’s knife, smash garlic cloves to a paste. Transfer to a medium bowl.

Step 5

Finely chop caramelized onions and transfer to bowl with garlic.

Step 6

Add 1½ cups yogurt and 2 tsp. lemon juice; season with salt and lot of pepper. Stir to combine.

Step 7

Cut 1 bunch radishes in half and arrange on a platter. Sprinkle dip with cayenne pepper. Serve radishes and chips alongside.