1. Make the grits: Place grits in a bowl, and cover with cold water by about 3 inches. Stir grits so that bits of husk rise to the top; pour off top layer of water. Strain through a fine sieve, and transfer to a medium saucepan. Gradually whisk in 5 cups water and 1 teaspoon salt. Bring to a simmer, whisking, until beginning to thicken. Reduce heat, and simmer gently, stirring occasionally and scraping bottom and sides of pan with a wooden spoon, until thick and creamy, about 45 minutes. Remove from heat. Let stand, covered, for 30 minutes or up to 1 hour.

2. Meanwhile, make the shrimp: Cook bacon in a large skillet over medium heat until beginning to crisp, about 5 minutes; transfer to a plate using a slotted spoon. Cook garlic, onion, and bell pepper in bacon fat, stirring occasionally, until just tender but not browned, 2 to 3 minutes.

3. Season shrimp on both sides with salt and pepper. Raise heat to medium-high; push vegetables to edge of skillet. Add oil, and heat until shimmering. Sear shrimp in a single layer for 2 minutes. Flip, and sear for 1 minute. Push shrimp to edge of skillet; sprinkle flour into center. Cook, stirring flour into vegetable-shrimp mixture, for 2 minutes. Add stock. Simmer, stirring, until sauce thickens, about 2 minutes. Add lemon juice, and stir in reserved bacon. Season with salt and pepper.

4. Just before serving, heat grits over medium-low. Stir in cheese and butter; season with salt and pepper. Serve shrimp over grits on warmed plates.