Heat oven to 425 degrees F. Spray an 8-by-8-inch square glass or ceramic baking pan with cooking spray.

In a small saucepan over medium-high heat, bring water, milk and garlic just to a boil. Reduce heat to low; stir in polenta and dried oregano. Cook, stirring often, 7 to 10 minutes until polenta is thick and smooth. Remove from heat. Stir in salt and pepper to taste, shredded cheese and lemon zest.

Spread polenta mixture evenly in bottom of prepared baking pan. Bake 40 to 45 minutes until top of polenta is golden brown. Set aside to cool.

Meanwhile, make the relish: Use a sharp knife to slice off kernels from ears of corn. Transfer corn kernels to a large bowl. Slice half of blueberries in half, leaving the rest intact. Add sliced and whole blueberries to bowl, along with chopped red onion, thyme leaves, olive oil, vinegar and salt. Stir to combine.

Cut cooled polenta into squares or use a round cookie cutter to cut polenta into circles. Top with relish just before serving.