For the Fish:

1. In a medium bowl, mix pesto and breadcrumbs together until they form a coarse paste. Taste and add seasoning as necessary.
2. Place mahi-mahi portions on a large baking sheet.
3. Spread pesto mixture evenly across all four mahi-mahi portions. Use your fingers to pat the pesto mixture down into the fish to form an even crust.
4. Bake mahi-mahi at 375 for 12-16 minutes, until cooked through. Fish should reach an internal temperature of approximately 145 degrees fahrenheit.

For the Tomatoes:

1. While the fish cooks, prepare the blistered tomatoes.
2. Heat olive oil over medium-high heat in a cast iron skillet. When oil simmers, add tomatoes and garlic clove and let cook without stirring for 2-3 minutes. The tomatoes will pop and sizzle a bit, so keep an eye out for flying oil or tomato juice.
3. Season tomatoes with salt and pepper to taste.
4. When tomatoes have begun to blister, give them a stir to turn them over so that the other sides can start to blister as well. Cook an additional 2-3 minutes without stirring, until tomatoes are softened and have charred and blistered on all sides.

For the Sauce:

1. Heat oil in a medium, nonreactive skillet over medium heat.
2. When oil simmers, add shallot and sauté for 1 minute until shallot has softened.
3. Whisk in lemon juice, lemon zest, salt, and pepper and remove sauce from heat. Let cool 2-3 minutes, until sauce has stopped simmering but is still warm.
4. Whisk in butter 1 pat at a time, whisking constantly after each addition until the whole pat is melted into the sauce before adding another.
5. Continue whisking in butter pats until all butter is incorporated into the sauce. Serve immediately.
6. If your sauce breaks, don't worry - just give it a zap with an immersion blender to emulsify it again and bring it all back together.

To assemble:

1. Drizzle a bit of sauce on the bottom of a plate or pasta bowl. Place pesto crusted mahi-mahi on top of the sauce and top with blistered tomatoes. Add a lemon wedge for garnish and serve immediately.