How to Make It
Cook pancetta in a large skillet over medium, stirring occasionally, until fat is rendered, 8 to 10 minutes.
Add onion, garlic, and 1/4 teaspoon salt, and cook, stirring often, until onion is translucent, about 5 minutes.
Add tomatoes and remaining 1/4 teaspoon salt, and cook, tossing mixture and shaking skillet to coat tomatoes in pancetta fat, until tomatoes burst, about 8 minutes. Cook, gently shaking skillet, until juices and fat emulsify. Season to taste with salt.
Spread toast with ricotta, and top with tomato mixture. Serve immediately.